Merge pull request #3395 from MicrosoftDocs/user/leahtu/whats-new-134

What's New in DevTools (Microsoft Edge 134)

Author: captainbrosset

microsoft-edge/devtools-guide-chromium/whats-new/2025/03/devtools-134-images/forced-reflow.png

@@ -0,0 +1,74 @@
+---
+title: What's New in DevTools (Microsoft Edge 134)
+description: "Forced reflow in the Performance Insights sidebar. Heap snapshot statistics account for every byte. Simplified DevTools Themes menu. And more."
+author: MSEdgeTeam
+ms.author: msedgedevrel
+ms.topic: conceptual
+ms.service: microsoft-edge
+ms.subservice: devtools
+ms.date: 03/06/2025
+---
+# What's New in DevTools (Microsoft Edge 134)
+
+These are the latest features in the Stable release of Microsoft Edge DevTools.
+
+
+<!-- ====================================================================== -->
+## Forced reflow in the Performance Insights sidebar
+
+<!-- Subtitle: View the top function call and its total reflow time in your performance trace. -->
+
+The **Performance Insights** sidebar includes a new section called **Forced Reflow**.  This insight highlights the most time-consuming function call, showing its total reflow time and related stack traces.  By clicking on this insight, you can see the function call and its stack trace highlighted in the **Main** frame:
+
+![Forced reflow insight in the sidebar](./devtools-134-images/forced-reflow.png)
+
+
+<!-- ====================================================================== -->
+## Heap snapshot statistics account for every byte  
+
+<!-- Subtitle: View a memory allocation pie chart of your heap snapshot under Statistics-->
+
+Previously, when you took a heap snapshot in the **Memory** tool, the **Statistics** pie chart didn't show every byte that's in the categories, resulting in blank parts of the chart:
+
+![Heap snapshot statistic view before](./devtools-134-images/heap-snapshot-statistics-before.png)
+
+To fix this, two new catch-all categories have been added, to account for the rest of the bytes in the heap snapshot:
+* **Other JS objects**
+* **Other non-JS objects (such as HTML and CSS)**
+
+![Heap snapshot statistic view after](./devtools-134-images/heap-snapshot-statistics-after.png)
+
+
+<!-- ====================================================================== -->
+## Simplified DevTools Themes menu
+
+<!-- Subtitle: Change the DevTools theme by clicking Customize and control DevTools > Themes, and then select Light or Dark. -->
+
+The theme options have been simplified by removing the redundant nesting options.  When you go to **Customize and control DevTools** > **Themes**, the options have been simplified to **System preference**, **Light**, and **Dark**:
+
+![DevTools Themes menu options](./devtools-134-images/theme-options.png)
+
+
+<!-- ====================================================================== -->
+## Announcements from the Chromium project
+<!-- https://developer.chrome.com/blog/new-in-devtools-134 -->
+
+Microsoft Edge 134 also includes the following updates from the Chromium project:
+
+* [Privacy and security panel](https://developer.chrome.com/blog/new-in-devtools-134#privacy-and-security)
+* [Performance panel improvements](https://developer.chrome.com/blog/new-in-devtools-134#perf)
+   * [Calibrated CPU throttling presets](https://developer.chrome.com/blog/new-in-devtools-134#calibrated-cpu-throttling)
+   * [First- and third-party highlighting in Performance](https://developer.chrome.com/blog/new-in-devtools-134#perf-third-party)
+   * ['Optimize DOM size' insight](https://developer.chrome.com/blog/new-in-devtools-134#dom-size)
+   * [Extend the performance trace with console.timeStamp](https://developer.chrome.com/blog/new-in-devtools-134#console-timestamp)
+* [Elements panel improvements](https://developer.chrome.com/blog/new-in-devtools-134#elements)
+   * [Support for :open pseudo-class and various pseudo-elements](https://developer.chrome.com/blog/new-in-devtools-134#pseudo)
+* [Copy all console messages](https://developer.chrome.com/blog/new-in-devtools-134#copy-console)
+* [Byte units in the Memory panel](https://developer.chrome.com/blog/new-in-devtools-134#byte-units)
+
+
+<!-- ====================================================================== -->
+## See also
+
+* [What's New in Microsoft Edge DevTools](../../whats-new.md)
+* [Release notes for Microsoft Edge web platform](../../../../web-platform/release-notes/index.md)

microsoft-edge/devtools-guide-chromium/whats-new/2025/03/devtools-134-images/heap-snapshot-statistics-after.png

@@ -71,6 +71,10 @@
               href: ./devtools-guide-chromium/whats-new/whats-new.md
               displayName: release notes, announcements
 # latest 10 What's New
+            - name: Microsoft Edge 134
+              href: ./devtools-guide-chromium/whats-new/2025/03/devtools-134.md
+              displayName: What's New in DevTools (Microsoft Edge 134)  # page title
+
             - name: Microsoft Edge 133
               href: ./devtools-guide-chromium/whats-new/2025/02/devtools-133.md
               displayName: What's New in DevTools (Microsoft Edge 133)  # page title
@@ -107,16 +111,16 @@
               href: ./devtools-guide-chromium/whats-new/2024/05/devtools-125.md
               displayName: What's New in DevTools (Microsoft Edge 125)  # page title
 
-            - name: Microsoft Edge 124
-              href: ./devtools-guide-chromium/whats-new/2024/04/devtools-124.md
-              displayName: What's New in DevTools (Microsoft Edge 124)  # page title
-
             # keep 10 items above
             - name: Archive
               items:
                 - name: What's New in DevTools archive
                   href: ./devtools-guide-chromium/whats-new/whats-new-archive.md
 
+                - name: Microsoft Edge 124
+                  href: ./devtools-guide-chromium/whats-new/2024/04/devtools-124.md
+                  displayName: What's New in DevTools (Microsoft Edge 124)  # page title
+
                 - name: Microsoft Edge 123
                   href: ./devtools-guide-chromium/whats-new/2024/03/devtools-123.md
                   displayName: What's New in DevTools (Microsoft Edge 123)  # page title