--- a/devtools/client/webconsole/new-console-output/test/fixtures/moz.build
+++ b/devtools/client/webconsole/new-console-output/test/fixtures/moz.build
@@ -1,8 +1,9 @@
 # vim: set filetype=python:
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 DIRS += [
-    'stub-generators'
+    'stub-generators',
+    'stubs'
 ]

--- a/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/head.js
+++ b/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/head.js
@@ -13,28 +13,130 @@ Services.scriptloader.loadSubScript(
   this);
 
 Services.prefs.setBoolPref("devtools.webconsole.new-frontend-enabled", true);
 registerCleanupFunction(() => {
   Services.prefs.clearUserPref("devtools.webconsole.new-frontend-enabled");
 });
 
 const { prepareMessage } = require("devtools/client/webconsole/new-console-output/utils/messages");
+const { stubPackets } = require("devtools/client/webconsole/new-console-output/test/fixtures/stubs/index.js");
 
 const BASE_PATH = "../../../../devtools/client/webconsole/new-console-output/test/fixtures";
 const TEMP_FILE_PATH = OS.Path.join(`${BASE_PATH}/stub-generators`, "test-tempfile.js");
 
+let cachedPackets = {};
+
+function getCleanedPacket(key, packet) {
+  if(Object.keys(cachedPackets).includes(key)) {
+    return cachedPackets[key];
+  }
+
+  // Strip escaped characters.
+  let safeKey = key
+    .replace(/\\n/g, "\n")
+    .replace(/\\r/g, "\r")
+    .replace(/\\\"/g, `\"`)
+    .replace(/\\\'/g, `\'`);
+
+  // If the stub already exist, we want to ignore irrelevant properties
+  // (actor, timeStamp, timer, ...) that might changed and "pollute"
+  // the diff resulting from this stub generation.
+  let res;
+  if(stubPackets.has(safeKey)) {
+
+    let existingPacket = stubPackets.get(safeKey);
+    res = Object.assign({}, packet, {
+      from: existingPacket.from
+    });
+
+    // Clean root timestamp.
+    if(res.timestamp) {
+      res.timestamp = existingPacket.timestamp;
+    }
+
+    if (res.message) {
+      // Clean timeStamp on the message prop.
+      res.message.timeStamp = existingPacket.message.timeStamp;
+      if (res.message.timer) {
+        // Clean timer properties on the message.
+        // Those properties are found on console.time and console.timeEnd calls,
+        // and those time can vary, which is why we need to clean them.
+        if (res.message.timer.started) {
+          res.message.timer.started = existingPacket.message.timer.started;
+        }
+        if (res.message.timer.duration) {
+          res.message.timer.duration = existingPacket.message.timer.duration;
+        }
+      }
+
+      if(Array.isArray(res.message.arguments)) {
+        // Clean actor ids on each message.arguments item.
+        res.message.arguments.forEach((argument, i) => {
+          if (argument && argument.actor) {
+            argument.actor = existingPacket.message.arguments[i].actor;
+          }
+        });
+      }
+    }
+
+    if (res.result) {
+      // Clean actor ids on evaluation result messages.
+      res.result.actor = existingPacket.result.actor;
+      if (res.result.preview) {
+        if(res.result.preview.timestamp) {
+          // Clean timestamp there too.
+          res.result.preview.timestamp = existingPacket.result.preview.timestamp;
+        }
+      }
+    }
+
+    if (res.exception) {
+      // Clean actor ids on exception messages.
+      res.exception.actor = existingPacket.exception.actor;
+      if (res.exception.preview) {
+        if(res.exception.preview.timestamp) {
+          // Clean timestamp there too.
+          res.exception.preview.timestamp = existingPacket.exception.preview.timestamp;
+        }
+      }
+    }
+
+    if (res.eventActor) {
+      // Clean actor ids, timeStamp and startedDateTime on network messages.
+      res.eventActor.actor = existingPacket.eventActor.actor;
+      res.eventActor.startedDateTime = existingPacket.eventActor.startedDateTime;
+      res.eventActor.timeStamp = existingPacket.eventActor.timeStamp;
+    }
+
+    if (res.pageError) {
+      // Clean timeStamp on pageError messages.
+      res.pageError.timeStamp = existingPacket.pageError.timeStamp;
+    }
+
+  } else {
+    res = packet;
+  }
+
+  cachedPackets[key] = res;
+  return res;
+}
+
 function formatPacket(key, packet) {
   return `
-stubPackets.set("${key}", ${JSON.stringify(packet, null, "\t")});
+stubPackets.set("${key}", ${JSON.stringify(getCleanedPacket(key, packet), null, "\t")});
 `;
 }
 
-function formatStub(key, message) {
-  let prepared = prepareMessage(message, {getNextId: () => "1"});
+function formatStub(key, packet) {
+  let prepared = prepareMessage(
+    getCleanedPacket(key, packet),
+    {getNextId: () => "1"}
+  );
+
   return `
 stubPreparedMessages.set("${key}", new ConsoleMessage(${JSON.stringify(prepared, null, "\t")}));
 `;
 }
 
 function formatNetworkStub(key, packet) {
   let actor = packet.eventActor;
   let networkInfo = {

new file mode 100644
--- /dev/null
+++ b/devtools/client/webconsole/new-console-output/test/fixtures/stubs/moz.build
@@ -0,0 +1,11 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+DevToolsModules(
+  'consoleApi.js',
+  'evaluationResult.js',
+  'index.js',
+  'networkEvent.js',
+  'pageError.js',
+)