--- a/devtools/client/netmonitor/src/components/RequestListColumnTime.js
+++ b/devtools/client/netmonitor/src/components/RequestListColumnTime.js
@@ -24,17 +24,17 @@ const {
  * - Response Time
  * - Duration Time
  * - Latency Time
  */
 class RequestListColumnTime extends Component {
   static get propTypes() {
     return {
       connector: PropTypes.object.isRequired,
-      firstRequestStartedMillis: PropTypes.number.isRequired,
+      firstRequestStartedMs: PropTypes.number.isRequired,
       item: PropTypes.object.isRequired,
       type: PropTypes.oneOf(["start", "end", "response", "duration", "latency"])
         .isRequired,
     };
   }
 
   componentDidMount() {
     const { item, connector } = this.props;
@@ -46,25 +46,25 @@ class RequestListColumnTime extends Comp
     fetchNetworkUpdatePacket(connector.requestData, item, ["eventTimings"]);
   }
 
   shouldComponentUpdate(nextProps) {
     return this.getTime(this.props) !== this.getTime(nextProps);
   }
 
   getTime(props) {
-    const { firstRequestStartedMillis, item, type } = props;
+    const { firstRequestStartedMs, item, type } = props;
 
     switch (type) {
       case "start":
-        return getStartTime(item, firstRequestStartedMillis);
+        return getStartTime(item, firstRequestStartedMs);
       case "end":
-        return getEndTime(item, firstRequestStartedMillis);
+        return getEndTime(item, firstRequestStartedMs);
       case "response":
-        return getResponseTime(item, firstRequestStartedMillis);
+        return getResponseTime(item, firstRequestStartedMs);
       case "duration":
         return item.totalTime;
       case "latency":
         return item.eventTimings ? item.eventTimings.timings.wait : undefined;
     }
 
     return 0;
   }

--- a/devtools/client/netmonitor/src/components/RequestListColumnWaterfall.js
+++ b/devtools/client/netmonitor/src/components/RequestListColumnWaterfall.js
@@ -25,17 +25,17 @@ const UPDATED_WATERFALL_PROPS = [
   "fromServiceWorker",
   "totalTime",
 ];
 
 class RequestListColumnWaterfall extends Component {
   static get propTypes() {
     return {
       connector: PropTypes.object.isRequired,
-      firstRequestStartedMillis: PropTypes.number.isRequired,
+      firstRequestStartedMs: PropTypes.number.isRequired,
       item: PropTypes.object.isRequired,
       onWaterfallMouseDown: PropTypes.func.isRequired,
     };
   }
 
   componentDidMount() {
     const { connector, item } = this.props;
     fetchNetworkUpdatePacket(connector.requestData, item, ["eventTimings"]);
@@ -47,19 +47,17 @@ class RequestListColumnWaterfall extends
   }
 
   shouldComponentUpdate(nextProps) {
     return (
       !propertiesEqual(
         UPDATED_WATERFALL_PROPS,
         this.props.item,
         nextProps.item
-      ) ||
-      this.props.firstRequestStartedMillis !==
-        nextProps.firstRequestStartedMillis
+      ) || this.props.firstRequestStartedMs !== nextProps.firstRequestStartedMs
     );
   }
 
   timingTooltip() {
     const {
       eventTimings,
       fromCache,
       fromServiceWorker,
@@ -137,37 +135,32 @@ class RequestListColumnWaterfall extends
         )
       );
     }
 
     return boxes;
   }
 
   render() {
-    const {
-      firstRequestStartedMillis,
-      item,
-      onWaterfallMouseDown,
-    } = this.props;
+    const { firstRequestStartedMs, item, onWaterfallMouseDown } = this.props;
 
     return dom.td(
       {
         className: "requests-list-column requests-list-waterfall",
         onMouseOver: ({ target }) => {
           if (!target.title) {
             target.title = this.timingTooltip();
           }
         },
       },
       div(
         {
           className: "requests-list-timings",
           style: {
-            paddingInlineStart: `${item.startedMillis -
-              firstRequestStartedMillis}px`,
+            paddingInlineStart: `${item.startedMs - firstRequestStartedMs}px`,
           },
           onMouseDown: onWaterfallMouseDown,
         },
         this.timingBoxes()
       )
     );
   }
 }

--- a/devtools/client/netmonitor/src/components/RequestListContent.js
+++ b/devtools/client/netmonitor/src/components/RequestListContent.js
@@ -69,17 +69,17 @@ class RequestListContent extends Compone
       networkDetailsOpen: PropTypes.bool.isRequired,
       networkDetailsWidth: PropTypes.number,
       networkDetailsHeight: PropTypes.number,
       cloneRequest: PropTypes.func.isRequired,
       clickedRequest: PropTypes.object,
       openDetailsPanelTab: PropTypes.func.isRequired,
       sendCustomRequest: PropTypes.func.isRequired,
       displayedRequests: PropTypes.array.isRequired,
-      firstRequestStartedMillis: PropTypes.number.isRequired,
+      firstRequestStartedMs: PropTypes.number.isRequired,
       fromCache: PropTypes.bool,
       onCauseBadgeMouseDown: PropTypes.func.isRequired,
       onItemRightMouseButtonDown: PropTypes.func.isRequired,
       onItemMouseDown: PropTypes.func.isRequired,
       onSecurityIconMouseDown: PropTypes.func.isRequired,
       onSelectDelta: PropTypes.func.isRequired,
       onWaterfallMouseDown: PropTypes.func.isRequired,
       openStatistics: PropTypes.func.isRequired,
@@ -334,17 +334,17 @@ class RequestListContent extends Compone
     this.shouldScrollBottom = false;
   }
 
   render() {
     const {
       connector,
       columns,
       displayedRequests,
-      firstRequestStartedMillis,
+      firstRequestStartedMs,
       onCauseBadgeMouseDown,
       onSecurityIconMouseDown,
       onWaterfallMouseDown,
       requestFilterTypes,
       scale,
       selectedRequest,
     } = this.props;
 
@@ -367,17 +367,17 @@ class RequestListContent extends Compone
             style: {
               "--timings-scale": scale,
               "--timings-rev-scale": 1 / scale,
             },
           },
           displayedRequests.map((item, index) =>
             RequestListItem({
               blocked: !!item.blockedReason,
-              firstRequestStartedMillis,
+              firstRequestStartedMs,
               fromCache: item.status === "304" || item.fromCache,
               connector,
               columns,
               item,
               index,
               isSelected: item.id === (selectedRequest && selectedRequest.id),
               key: item.id,
               onContextMenu: this.onContextMenu,
@@ -401,17 +401,17 @@ class RequestListContent extends Compone
 module.exports = connect(
   state => ({
     columns: state.ui.columns,
     networkDetailsOpen: state.ui.networkDetailsOpen,
     networkDetailsWidth: state.ui.networkDetailsWidth,
     networkDetailsHeight: state.ui.networkDetailsHeight,
     clickedRequest: state.requests.clickedRequest,
     displayedRequests: getDisplayedRequests(state),
-    firstRequestStartedMillis: state.requests.firstStartedMillis,
+    firstRequestStartedMs: state.requests.firstStartedMs,
     selectedRequest: getSelectedRequest(state),
     scale: getWaterfallScale(state),
     requestFilterTypes: state.filters.requestFilterTypes,
   }),
   (dispatch, props) => ({
     blockSelectedRequestURL: clickedRequest => {
       dispatch(
         Actions.blockSelectedRequestURL(props.connector, clickedRequest)

--- a/devtools/client/netmonitor/src/components/RequestListHeader.js
+++ b/devtools/client/netmonitor/src/components/RequestListHeader.js
@@ -598,17 +598,17 @@ class RequestListHeader extends Componen
     );
   }
 }
 
 module.exports = connect(
   state => ({
     columns: state.ui.columns,
     columnsData: state.ui.columnsData,
-    firstRequestStartedMillis: state.requests.firstStartedMillis,
+    firstRequestStartedMs: state.requests.firstStartedMs,
     scale: getWaterfallScale(state),
     sort: state.sort,
     timingMarkers: state.timingMarkers,
     waterfallWidth: state.ui.waterfallWidth,
   }),
   dispatch => ({
     resetColumns: () => dispatch(Actions.resetColumns()),
     resetSorting: () => dispatch(Actions.sortBy(null)),

--- a/devtools/client/netmonitor/src/components/RequestListItem.js
+++ b/devtools/client/netmonitor/src/components/RequestListItem.js
@@ -105,26 +105,26 @@ const UPDATED_REQ_ITEM_PROPS = [
   "isRacing",
   "fromServiceWorker",
   "method",
   "url",
   "remoteAddress",
   "cause",
   "contentSize",
   "transferredSize",
-  "startedMillis",
+  "startedMs",
   "totalTime",
   "requestCookies",
   "requestHeaders",
   "responseCookies",
   "responseHeaders",
 ];
 
 const UPDATED_REQ_PROPS = [
-  "firstRequestStartedMillis",
+  "firstRequestStartedMs",
   "index",
   "isSelected",
   "requestFilterTypes",
   "waterfallWidth",
 ];
 
 /**
  * Used by render: renders the given ColumnComponent if the flag for this column
@@ -165,53 +165,53 @@ const COLUMN_COMPONENTS = [
     ColumnComponent: RequestListColumnSetCookies,
     props: ["connector"],
   },
   { column: "transferred", ColumnComponent: RequestListColumnTransferredSize },
   { column: "contentSize", ColumnComponent: RequestListColumnContentSize },
   {
     column: "startTime",
     ColumnComponent: RequestListColumnTime,
-    props: ["connector", "firstRequestStartedMillis", { type: "start" }],
+    props: ["connector", "firstRequestStartedMs", { type: "start" }],
   },
   {
     column: "endTime",
     ColumnComponent: RequestListColumnTime,
-    props: ["connector", "firstRequestStartedMillis", { type: "end" }],
+    props: ["connector", "firstRequestStartedMs", { type: "end" }],
   },
   {
     column: "responseTime",
     ColumnComponent: RequestListColumnTime,
-    props: ["connector", "firstRequestStartedMillis", { type: "response" }],
+    props: ["connector", "firstRequestStartedMs", { type: "response" }],
   },
   {
     column: "duration",
     ColumnComponent: RequestListColumnTime,
-    props: ["connector", "firstRequestStartedMillis", { type: "duration" }],
+    props: ["connector", "firstRequestStartedMs", { type: "duration" }],
   },
   {
     column: "latency",
     ColumnComponent: RequestListColumnTime,
-    props: ["connector", "firstRequestStartedMillis", { type: "latency" }],
+    props: ["connector", "firstRequestStartedMs", { type: "latency" }],
   },
 ];
 
 /**
  * Render one row in the request list.
  */
 class RequestListItem extends Component {
   static get propTypes() {
     return {
       blocked: PropTypes.bool,
       connector: PropTypes.object.isRequired,
       columns: PropTypes.object.isRequired,
       item: PropTypes.object.isRequired,
       index: PropTypes.number.isRequired,
       isSelected: PropTypes.bool.isRequired,
-      firstRequestStartedMillis: PropTypes.number.isRequired,
+      firstRequestStartedMs: PropTypes.number.isRequired,
       fromCache: PropTypes.bool,
       onCauseBadgeMouseDown: PropTypes.func.isRequired,
       onDoubleClick: PropTypes.func.isRequired,
       onContextMenu: PropTypes.func.isRequired,
       onFocusedNodeChange: PropTypes.func,
       onMouseDown: PropTypes.func.isRequired,
       onSecurityIconMouseDown: PropTypes.func.isRequired,
       onWaterfallMouseDown: PropTypes.func.isRequired,
@@ -270,17 +270,17 @@ class RequestListItem extends Component 
   render() {
     const {
       blocked,
       connector,
       columns,
       item,
       index,
       isSelected,
-      firstRequestStartedMillis,
+      firstRequestStartedMs,
       fromCache,
       onDoubleClick,
       onContextMenu,
       onMouseDown,
       onWaterfallMouseDown,
     } = this.props;
 
     const classList = ["request-list-item", index % 2 ? "odd" : "even"];
@@ -321,17 +321,17 @@ class RequestListItem extends Component 
           connector,
           item,
           header,
         })
       ),
       columns.waterfall &&
         RequestListColumnWaterfall({
           connector,
-          firstRequestStartedMillis,
+          firstRequestStartedMs,
           item,
           onWaterfallMouseDown,
         })
     );
   }
 }
 
 module.exports = RequestListItem;

--- a/devtools/client/netmonitor/src/components/StatusBar.js
+++ b/devtools/client/netmonitor/src/components/StatusBar.js
@@ -33,22 +33,17 @@ const TOOLTIP_TRANSFERRED = L10N.getStr(
   "networkMenu.summary.tooltip.transferred"
 );
 const TOOLTIP_FINISH = L10N.getStr("networkMenu.summary.tooltip.finish");
 const TOOLTIP_DOM_CONTENT_LOADED = L10N.getStr(
   "networkMenu.summary.tooltip.domContentLoaded"
 );
 const TOOLTIP_LOAD = L10N.getStr("networkMenu.summary.tooltip.load");
 
-const UPDATED_SUMMARY_PROPS = [
-  "count",
-  "contentSize",
-  "transferredSize",
-  "millis",
-];
+const UPDATED_SUMMARY_PROPS = ["count", "contentSize", "transferredSize", "ms"];
 
 const UPDATED_TIMING_PROPS = ["DOMContentLoaded", "load"];
 
 /**
  * Status Bar component
  * Displays the summary of total size and transferred size by all requests
  * Also displays different timing markers
  */
@@ -71,34 +66,34 @@ class StatusBar extends Component {
         timingMarkers,
         nextProps.timingMarkers
       )
     );
   }
 
   render() {
     const { openStatistics, summary, timingMarkers } = this.props;
-    const { count, contentSize, transferredSize, millis } = summary;
+    const { count, contentSize, transferredSize, ms } = summary;
     const { DOMContentLoaded, load } = timingMarkers;
 
     const countText =
       count === 0
         ? REQUESTS_COUNT_EMPTY
         : PluralForm.get(
             count,
             L10N.getStr("networkMenu.summary.requestsCount2")
           ).replace("#1", count);
     const transferText = L10N.getFormatStrWithNumbers(
       "networkMenu.summary.transferred",
       getFormattedSize(contentSize),
       getFormattedSize(transferredSize)
     );
     const finishText = L10N.getFormatStrWithNumbers(
       "networkMenu.summary.finish",
-      getFormattedTime(millis)
+      getFormattedTime(ms)
     );
 
     return div(
       { className: "devtools-toolbar devtools-toolbar-bottom" },
       button(
         {
           className: "devtools-button requests-list-network-summary-button",
           title: TOOLTIP_PERF,

--- a/devtools/client/netmonitor/src/components/websockets/StatusBar.js
+++ b/devtools/client/netmonitor/src/components/websockets/StatusBar.js
@@ -33,17 +33,17 @@ const TOOLTIP_FRAMES_COUNT = L10N.getStr
 );
 const TOOLTIP_FRAMES_TOTAL_SIZE = L10N.getStr(
   "networkMenu.ws.summary.tooltip.framesTotalSize"
 );
 const TOOLTIP_FRAMES_TOTAL_TIME = L10N.getStr(
   "networkMenu.ws.summary.tooltip.framesTotalTime"
 );
 
-const UPDATED_WS_SUMMARY_PROPS = ["count", "totalMillis", "totalSize"];
+const UPDATED_WS_SUMMARY_PROPS = ["count", "totalMs", "totalSize"];
 
 /**
  * Displays the summary of frame count, total size and total time since the first frame.
  */
 class StatusBar extends Component {
   static get propTypes() {
     return {
       summary: PropTypes.object.isRequired,
@@ -56,27 +56,27 @@ class StatusBar extends Component {
       UPDATED_WS_SUMMARY_PROPS,
       summary,
       nextProps.summary
     );
   }
 
   render() {
     const { summary } = this.props;
-    const { count, totalSize, totalMillis } = summary;
+    const { count, totalSize, totalMs } = summary;
 
     const countText =
       count === 0
         ? FRAMES_COUNT_EMPTY
         : PluralForm.get(
             count,
             L10N.getStr("networkMenu.ws.summary.framesCount2")
           ).replace("#1", count);
     const totalSizeText = getFormattedSize(totalSize);
-    const totalMillisText = getFormattedTime(totalMillis);
+    const totalMillisText = getFormattedTime(totalMs);
 
     return footer(
       { className: "devtools-toolbar devtools-toolbar-bottom" },
       div(
         {
           className: "status-bar-label frames-list-network-summary-count",
           title: TOOLTIP_FRAMES_COUNT,
         },

--- a/devtools/client/netmonitor/src/connector/chrome/events.js
+++ b/devtools/client/netmonitor/src/connector/chrome/events.js
@@ -212,17 +212,17 @@ class CDPConnector {
       fromCache,
       fromServiceWorker,
     } = data;
 
     this.actions
       .addRequest(
         id,
         {
-          startedMillis: startedDateTime,
+          startedMs: startedDateTime,
           method,
           url,
           isXHR,
           cause,
           fromCache,
           fromServiceWorker,
         },
         true

--- a/devtools/client/netmonitor/src/connector/firefox-data-provider.js
+++ b/devtools/client/netmonitor/src/connector/firefox-data-provider.js
@@ -88,17 +88,17 @@ class FirefoxDataProvider {
       blockedReason,
     });
 
     if (this.actionsEnabled && this.actions.addRequest) {
       await this.actions.addRequest(
         id,
         {
           // Convert the received date/time string to a unix timestamp.
-          startedMillis: Date.parse(startedDateTime),
+          startedMs: Date.parse(startedDateTime),
           method,
           url,
           isXHR,
           cause,
 
           // Compatibility code to support Firefox 58 and earlier that always
           // send stack-trace immediately on networkEvent message.
           // FF59+ supports fetching the traces lazily via requestData.

--- a/devtools/client/netmonitor/src/har/har-builder.js
+++ b/devtools/client/netmonitor/src/har/har-builder.js
@@ -96,17 +96,17 @@ HarBuilder.prototype = {
     return page;
   },
 
   buildEntry: async function(log, file) {
     const page = this.getPage(log, file);
 
     const entry = {};
     entry.pageref = page.id;
-    entry.startedDateTime = dateToJSON(new Date(file.startedMillis));
+    entry.startedDateTime = dateToJSON(new Date(file.startedMs));
 
     let eventTimings = file.eventTimings;
     if (!eventTimings && this._options.requestData) {
       eventTimings = await this._options.requestData(file.id, "eventTimings");
     }
 
     entry.request = await this.buildRequest(file);
     entry.response = await this.buildResponse(file);

--- a/devtools/client/netmonitor/src/har/har-collector.js
+++ b/devtools/client/netmonitor/src/har/har-collector.js
@@ -179,18 +179,18 @@ HarCollector.prototype = {
     if (file) {
       console.error(
         "HarCollector.onNetworkEvent; ERROR " + "existing file conflict!"
       );
       return;
     }
 
     file = {
-      startedDeltaMillis: startTime - this.firstRequestStart,
-      startedMillis: startTime,
+      startedDeltaMs: startTime - this.firstRequestStart,
+      startedMs: startTime,
       method: method,
       url: url,
       isXHR: isXHR,
     };
 
     this.files.set(actor, file);
 
     // Mimic the Net panel data structure

--- a/devtools/client/netmonitor/src/har/har-importer.js
+++ b/devtools/client/netmonitor/src/har/har-importer.js
@@ -33,23 +33,23 @@ HarImporter.prototype = {
     const pages = new Map();
     har.log.pages.forEach(page => {
       pages.set(page.id, page);
     });
 
     // Iterate all entries/requests and generate state.
     har.log.entries.forEach(entry => {
       const requestId = String(++guid);
-      const startedMillis = Date.parse(entry.startedDateTime);
+      const startedMs = Date.parse(entry.startedDateTime);
 
       // Add request
       this.actions.addRequest(
         requestId,
         {
-          startedMillis: startedMillis,
+          startedMs: startedMs,
           method: entry.request.method,
           url: entry.request.url,
           isXHR: false,
           cause: {
             loadingDocumentUri: "",
             stackTraceAvailable: false,
             type: "",
           },
@@ -136,24 +136,24 @@ HarImporter.prototype = {
       // Set 0 as the default value
       onContentLoad = onContentLoad != -1 ? onContentLoad : 0;
       onLoad = onLoad != -1 ? onLoad : 0;
 
       // Add timing markers
       if (onContentLoad > 0) {
         this.actions.addTimingMarker({
           name: "dom-interactive",
-          time: startedMillis + onContentLoad,
+          time: startedMs + onContentLoad,
         });
       }
 
       if (onLoad > 0) {
         this.actions.addTimingMarker({
           name: "dom-complete",
-          time: startedMillis + onLoad,
+          time: startedMs + onLoad,
         });
       }
     });
   },
 };
 
 // Exports from this module
 exports.HarImporter = HarImporter;

--- a/devtools/client/netmonitor/src/reducers/requests.js
+++ b/devtools/client/netmonitor/src/reducers/requests.js
@@ -32,18 +32,18 @@ function Requests() {
     // Map with all requests (key = actor ID, value = request object)
     requests: new Map(),
     // Selected request ID
     selectedId: null,
     preselectedId: null,
     // True if the monitor is recording HTTP traffic
     recording: true,
     // Auxiliary fields to hold requests stats
-    firstStartedMillis: +Infinity,
-    lastEndedMillis: -Infinity,
+    firstStartedMs: +Infinity,
+    lastEndedMs: -Infinity,
   };
 }
 
 /**
  * This reducer is responsible for maintaining list of request
  * within the Network panel.
  */
 function requestsReducer(state = Requests(), action) {
@@ -147,54 +147,53 @@ function addRequest(state, action) {
     id: action.id,
     ...action.data,
     urlDetails: getUrlDetails(action.data.url),
   };
 
   nextState.requests = mapSet(state.requests, newRequest.id, newRequest);
 
   // Update the started/ended timestamps.
-  const { startedMillis } = action.data;
-  if (startedMillis < state.firstStartedMillis) {
-    nextState.firstStartedMillis = startedMillis;
+  const { startedMs } = action.data;
+  if (startedMs < state.firstStartedMs) {
+    nextState.firstStartedMs = startedMs;
   }
-  if (startedMillis > state.lastEndedMillis) {
-    nextState.lastEndedMillis = startedMillis;
+  if (startedMs > state.lastEndedMs) {
+    nextState.lastEndedMs = startedMs;
   }
 
   // Select the request if it was preselected and there is no other selection.
   if (state.preselectedId && state.preselectedId === action.id) {
     nextState.selectedId = state.selectedId || state.preselectedId;
     nextState.preselectedId = null;
   }
 
   return nextState;
 }
 
 function updateRequest(state, action) {
-  const { requests, lastEndedMillis } = state;
+  const { requests, lastEndedMs } = state;
 
   let request = requests.get(action.id);
   if (!request) {
     return state;
   }
 
   request = {
     ...request,
     ...processNetworkUpdates(action.data, request),
   };
   const requestEndTime =
-    request.startedMillis +
+    request.startedMs +
     (request.eventTimings ? request.eventTimings.totalTime : 0);
 
   return {
     ...state,
     requests: mapSet(state.requests, action.id, request),
-    lastEndedMillis:
-      requestEndTime > lastEndedMillis ? requestEndTime : lastEndedMillis,
+    lastEndedMs: requestEndTime > lastEndedMs ? requestEndTime : lastEndedMs,
   };
 }
 
 function cloneRequest(state, id) {
   const { requests } = state;
 
   if (!id) {
     return state;

--- a/devtools/client/netmonitor/src/reducers/timing-markers.js
+++ b/devtools/client/netmonitor/src/reducers/timing-markers.js
@@ -16,19 +16,19 @@ function TimingMarkers() {
     firstDocumentDOMContentLoadedTimestamp: -1,
     firstDocumentLoadTimestamp: -1,
     firstDocumentRequestStartTimestamp: +Infinity,
   };
 }
 
 function addRequest(state, action) {
   const nextState = { ...state };
-  const { startedMillis } = action.data;
-  if (startedMillis < state.firstDocumentRequestStartTimestamp) {
-    nextState.firstDocumentRequestStartTimestamp = startedMillis;
+  const { startedMs } = action.data;
+  if (startedMs < state.firstDocumentRequestStartTimestamp) {
+    nextState.firstDocumentRequestStartTimestamp = startedMs;
   }
 
   return nextState;
 }
 
 function addTimingMarker(state, action) {
   state = { ...state };
 

--- a/devtools/client/netmonitor/src/selectors/requests.js
+++ b/devtools/client/netmonitor/src/selectors/requests.js
@@ -109,20 +109,20 @@ const getDisplayedRequests = createSelec
 const getTypeFilteredRequests = createSelector(
   state => state.requests,
   getTypeFilterFn,
   ({ requests }, filterFn) => [...requests.values()].filter(filterFn)
 );
 
 const getDisplayedRequestsSummary = createSelector(
   getDisplayedRequests,
-  state => state.requests.lastEndedMillis - state.requests.firstStartedMillis,
-  (requests, totalMillis) => {
+  state => state.requests.lastEndedMs - state.requests.firstStartedMs,
+  (requests, totalMs) => {
     if (requests.size == 0) {
-      return { count: 0, bytes: 0, millis: 0 };
+      return { count: 0, bytes: 0, ms: 0 };
     }
 
     const totalBytes = requests.reduce(
       (totals, item) => {
         if (typeof item.contentSize == "number") {
           totals.contentSize += item.contentSize;
         }
 
@@ -136,17 +136,17 @@ const getDisplayedRequestsSummary = crea
         return totals;
       },
       { contentSize: 0, transferredSize: 0 }
     );
 
     return {
       count: requests.size,
       contentSize: totalBytes.contentSize,
-      millis: totalMillis,
+      ms: totalMs,
       transferredSize: totalBytes.transferredSize,
     };
   }
 );
 
 const getSelectedRequest = createSelector(
   state => state.requests,
   ({ selectedId, requests }) =>

--- a/devtools/client/netmonitor/src/selectors/ui.js
+++ b/devtools/client/netmonitor/src/selectors/ui.js
@@ -9,29 +9,26 @@ const { REQUESTS_WATERFALL } = require("
 
 const EPSILON = 0.001;
 
 const getWaterfallScale = createSelector(
   state => state.requests,
   state => state.timingMarkers,
   state => state.ui,
   (requests, timingMarkers, ui) => {
-    if (
-      requests.firstStartedMillis === +Infinity ||
-      ui.waterfallWidth === null
-    ) {
+    if (requests.firstStartedMs === +Infinity || ui.waterfallWidth === null) {
       return null;
     }
 
-    const lastEventMillis = Math.max(
-      requests.lastEndedMillis,
+    const lastEventMs = Math.max(
+      requests.lastEndedMs,
       timingMarkers.firstDocumentDOMContentLoadedTimestamp,
       timingMarkers.firstDocumentLoadTimestamp
     );
-    const longestWidth = lastEventMillis - requests.firstStartedMillis;
+    const longestWidth = lastEventMs - requests.firstStartedMs;
 
     // Reduce 20px for the last request's requests-list-timings-total
     return Math.min(
       Math.max(
         (ui.waterfallWidth - REQUESTS_WATERFALL.LABEL_WIDTH - 20) /
           longestWidth,
         EPSILON
       ),

--- a/devtools/client/netmonitor/src/selectors/web-sockets.js
+++ b/devtools/client/netmonitor/src/selectors/web-sockets.js
@@ -55,33 +55,33 @@ const getSelectedFrame = createSelector(
 
 /**
  * Returns summary data of the list of frames that are visible to the user.
  * Filtered frames by types and text are factored in.
  */
 const getDisplayedFramesSummary = createSelector(
   getDisplayedFrames,
   displayedFrames => {
-    let firstStartedMillis = +Infinity;
-    let lastEndedMillis = -Infinity;
+    let firstStartedMs = +Infinity;
+    let lastEndedMs = -Infinity;
     let totalSize = 0;
 
     displayedFrames.forEach(frame => {
       totalSize += frame.payload.length;
-      if (frame.timeStamp < firstStartedMillis) {
-        firstStartedMillis = frame.timeStamp;
+      if (frame.timeStamp < firstStartedMs) {
+        firstStartedMs = frame.timeStamp;
       }
-      if (frame.timeStamp > lastEndedMillis) {
-        lastEndedMillis = frame.timeStamp;
+      if (frame.timeStamp > lastEndedMs) {
+        lastEndedMs = frame.timeStamp;
       }
     });
 
     return {
       count: displayedFrames.length,
-      totalMillis: (lastEndedMillis - firstStartedMillis) / 1000,
+      totalMs: (lastEndedMs - firstStartedMs) / 1000,
       totalSize,
     };
   }
 );
 
 module.exports = {
   getSelectedFrame,
   isSelectedFrameVisible,

--- a/devtools/client/netmonitor/src/utils/request-utils.js
+++ b/devtools/client/netmonitor/src/utils/request-utils.js
@@ -406,52 +406,49 @@ function ipToLong(ip) {
 function propertiesEqual(props, item1, item2) {
   return item1 === item2 || props.every(p => item1[p] === item2[p]);
 }
 
 /**
  * Calculate the start time of a request, which is the time from start
  * of 1st request until the start of this request.
  *
- * Without a firstRequestStartedMillis argument the wrong time will be returned.
+ * Without a firstRequestStartedMs argument the wrong time will be returned.
  * However, it can be omitted when comparing two start times and neither supplies
- * a firstRequestStartedMillis.
+ * a firstRequestStartedMs.
  */
-function getStartTime(item, firstRequestStartedMillis = 0) {
-  return item.startedMillis - firstRequestStartedMillis;
+function getStartTime(item, firstRequestStartedMs = 0) {
+  return item.startedMs - firstRequestStartedMs;
 }
 
 /**
  * Calculate the end time of a request, which is the time from start
  * of 1st request until the end of this response.
  *
- * Without a firstRequestStartedMillis argument the wrong time will be returned.
+ * Without a firstRequestStartedMs argument the wrong time will be returned.
  * However, it can be omitted when comparing two end times and neither supplies
- * a firstRequestStartedMillis.
+ * a firstRequestStartedMs.
  */
-function getEndTime(item, firstRequestStartedMillis = 0) {
-  const { startedMillis, totalTime } = item;
-  return startedMillis + totalTime - firstRequestStartedMillis;
+function getEndTime(item, firstRequestStartedMs = 0) {
+  const { startedMs, totalTime } = item;
+  return startedMs + totalTime - firstRequestStartedMs;
 }
 
 /**
  * Calculate the response time of a request, which is the time from start
  * of 1st request until the beginning of download of this response.
  *
- * Without a firstRequestStartedMillis argument the wrong time will be returned.
+ * Without a firstRequestStartedMs argument the wrong time will be returned.
  * However, it can be omitted when comparing two response times and neither supplies
- * a firstRequestStartedMillis.
+ * a firstRequestStartedMs.
  */
-function getResponseTime(item, firstRequestStartedMillis = 0) {
-  const { startedMillis, totalTime, eventTimings = { timings: {} } } = item;
+function getResponseTime(item, firstRequestStartedMs = 0) {
+  const { startedMs, totalTime, eventTimings = { timings: {} } } = item;
   return (
-    startedMillis +
-    totalTime -
-    firstRequestStartedMillis -
-    eventTimings.timings.receive
+    startedMs + totalTime - firstRequestStartedMs - eventTimings.timings.receive
   );
 }
 
 /**
  * Format the protocols used by the request.
  */
 function getFormattedProtocol(item) {
   const { httpVersion = "", responseHeaders = { headers: [] } } = item;

--- a/devtools/client/netmonitor/src/utils/sort-predicates.js
+++ b/devtools/client/netmonitor/src/utils/sort-predicates.js
@@ -30,17 +30,17 @@ const { RESPONSE_HEADERS } = require("..
 function compareValues(first, second) {
   if (first === second) {
     return 0;
   }
   return first > second ? 1 : -1;
 }
 
 function waterfall(first, second) {
-  const result = compareValues(first.startedMillis, second.startedMillis);
+  const result = compareValues(first.startedMs, second.startedMs);
   return result || compareValues(first.id, second.id);
 }
 
 function status(first, second) {
   const result = compareValues(first.status, second.status);
   return result || waterfall(first, second);
 }
 

--- a/devtools/client/netmonitor/src/widgets/WaterfallBackground.js
+++ b/devtools/client/netmonitor/src/widgets/WaterfallBackground.js
@@ -5,17 +5,17 @@
 "use strict";
 
 const { getColor } = require("devtools/client/shared/theme");
 const { colorUtils } = require("devtools/shared/css/color");
 const { REQUESTS_WATERFALL } = require("../constants");
 
 const HTML_NS = "http://www.w3.org/1999/xhtml";
 const STATE_KEYS = [
-  "firstRequestStartedMillis",
+  "firstRequestStartedMs",
   "scale",
   "timingMarkers",
   "waterfallWidth",
 ];
 
 /**
  * Creates the background displayed on each waterfall view in this container.
  */
@@ -105,17 +105,17 @@ class WaterfallBackground {
     }
 
     function drawTimestamp(timestamp, color) {
       if (timestamp === -1) {
         return;
       }
 
       const delta = Math.floor(
-        (timestamp - state.firstRequestStartedMillis) * state.scale
+        (timestamp - state.firstRequestStartedMs) * state.scale
       );
       drawPixelAt(delta, color);
     }
 
     const {
       DOMCONTENTLOADED_TICKS_COLOR,
       LOAD_TICKS_COLOR,
     } = REQUESTS_WATERFALL;

--- a/devtools/client/netmonitor/test/browser_net_footer-summary.js
+++ b/devtools/client/netmonitor/test/browser_net_footer-summary.js
@@ -90,21 +90,21 @@ add_task(async function() {
     );
 
     const valueFinish = document.querySelector(
       ".requests-list-network-summary-finish"
     ).textContent;
     info("Current summary finish: " + valueFinish);
     const expectedFinish = L10N.getFormatStrWithNumbers(
       "networkMenu.summary.finish",
-      getFormattedTime(requestsSummary.millis)
+      getFormattedTime(requestsSummary.ms)
     );
 
     info(`Computed total bytes: ${requestsSummary.bytes}`);
-    info(`Computed total millis: ${requestsSummary.millis}`);
+    info(`Computed total ms: ${requestsSummary.ms}`);
 
     is(valueCount, expectedCount, "The current summary count is correct.");
     is(
       valueTransfer,
       expectedTransfer,
       "The current summary transfer is correct."
     );
     is(valueFinish, expectedFinish, "The current summary finish is correct.");

--- a/devtools/client/netmonitor/test/browser_net_simple-request-data.js
+++ b/devtools/client/netmonitor/test/browser_net_simple-request-data.js
@@ -68,24 +68,24 @@ function test() {
       is(
         typeof requestItem.id,
         "string",
         "The attached request id is incorrect."
       );
       isnot(requestItem.id, "", "The attached request id should not be empty.");
 
       is(
-        typeof requestItem.startedMillis,
+        typeof requestItem.startedMs,
         "number",
-        "The attached startedMillis is incorrect."
+        "The attached startedMs is incorrect."
       );
       isnot(
-        requestItem.startedMillis,
+        requestItem.startedMs,
         0,
-        "The attached startedMillis should not be zero."
+        "The attached startedMs should not be zero."
       );
 
       is(
         requestItem.requestHeaders,
         undefined,
         "The requestHeaders should not yet be set."
       );
       is(