--- a/browser/base/content/tabbrowser-tabs.js
+++ b/browser/base/content/tabbrowser-tabs.js
@@ -1933,16 +1933,20 @@
       this.arrowScrollbox._updateScrollButtonsDisabledState();
 
       // If this browser isn't lazy (indicating it's probably created by
       // session restore), preload the next about:newtab if we don't
       // already have a preloaded browser.
       if (tab.linkedPanel) {
         NewTabPagePreloading.maybeCreatePreloadedBrowser(window);
       }
+
+      if (UserInteraction.running("browser.tabs.opening", window)) {
+        UserInteraction.finish("browser.tabs.opening", window);
+      }
     }
 
     _canAdvanceToTab(aTab) {
       return !aTab.closing;
     }
 
     getRelatedElement(aTab) {
       if (!aTab) {

--- a/browser/base/content/tabbrowser.js
+++ b/browser/base/content/tabbrowser.js
@@ -2465,16 +2465,20 @@
       // all callers of addTab that pass a params object need to pass
       // a valid triggeringPrincipal.
       if (!triggeringPrincipal) {
         throw new Error(
           "Required argument triggeringPrincipal missing within addTab"
         );
       }
 
+      if (!UserInteraction.running("browser.tabs.opening", window)) {
+        UserInteraction.start("browser.tabs.opening", "initting", window);
+      }
+
       // Don't use document.l10n.setAttributes because the FTL file is loaded
       // lazily and we won't be able to resolve the string.
       document
         .getElementById("History:UndoCloseTab")
         .setAttribute("data-l10n-args", JSON.stringify({ tabCount: 1 }));
       SessionStore.setLastClosedTabCount(window, 1);
 
       // if we're adding tabs, we're past interrupt mode, ditch the owner
@@ -2562,27 +2566,30 @@
         t.setAttribute("pinned", "true");
       }
 
       t.classList.add("tabbrowser-tab");
 
       this.tabContainer._unlockTabSizing();
 
       if (!animate) {
+        UserInteraction.update("browser.tabs.opening", "not-animated", window);
         t.setAttribute("fadein", "true");
 
         // Call _handleNewTab asynchronously as it needs to know if the
         // new tab is selected.
         setTimeout(
           function(tabContainer) {
             tabContainer._handleNewTab(t);
           },
           0,
           this.tabContainer
         );
+      } else {
+        UserInteraction.update("browser.tabs.opening", "animated", window);
       }
 
       let usingPreloadedContent = false;
       let b;
 
       try {
         if (!batchInsertingTabs) {
           // When we are not restoring a session, we need to know
@@ -3284,16 +3291,20 @@
       {
         animate,
         byMouse,
         skipPermitUnload,
         closeWindowWithLastTab,
         prewarmed,
       } = {}
     ) {
+      if (UserInteraction.running("browser.tabs.opening", window)) {
+        UserInteraction.finish("browser.tabs.opening", window);
+      }
+
       // Telemetry stopwatches may already be running if removeTab gets
       // called again for an already closing tab.
       if (
         !TelemetryStopwatch.running("FX_TAB_CLOSE_TIME_ANIM_MS", aTab) &&
         !TelemetryStopwatch.running("FX_TAB_CLOSE_TIME_NO_ANIM_MS", aTab)
       ) {
         // Speculatevely start both stopwatches now. We'll cancel one of
         // the two later depending on whether we're animating.

--- a/toolkit/components/telemetry/UserInteractions.yaml
+++ b/toolkit/components/telemetry/UserInteractions.yaml
@@ -21,12 +21,17 @@
 #   category: <category name>                          # mandatory
 #     name: <interaction name>                         # mandatory
 #       description: <description of user interaction> # mandatory
 #       bug_numbers: [<list of bug numbers>]           # mandatory
 #
 # Precise documentation for UserInteractions can be found at
 # https://firefox-source-docs.mozilla.org/toolkit/components/telemetry/collection/user-interactions.html
 
+browser.tabs:
+  opening:
+    description: A new tab is being opened.
+    bug_numbers: [1662160]
+
 testing:
   interaction:
     description: A user interaction just for testing.
     bug_numbers: [1661304]