WebView2 147.0.3912.86 causes aggressive EcoQoS/Efficiency Mode throttling on desktop PCs

[iamnotamit]

Summary

After WebView2 Runtime updated to 147.0.3912.86 on April 26, 2026, all Chromium-based apps on my system immediately began exhibiting aggressive Efficiency Mode (EcoQoS) throttling. This did not occur on the previous version.

Affected apps

All apps using the shared WebView2/Chromium runtime are affected, including:

• Google Chrome
• Claude desktop app (Electron)
• Microsoft Edge

System

• OS: Windows 11 (Version 25H2, Build 26200.8246)
• CPU: AMD Ryzen 7 9800X3D 8-Core Processor
• WebView2 Runtime: 147.0.3912.86 (installed 4/26/2026 at 12:22 AM)
• PC type: Desktop (no battery)

Steps to reproduce

1. Allow WebView2 to update to 147.0.3912.86
2. Open any Chromium-based app
3. Open Task Manager -> Processes
4. Observe multiple processes immediately placed into Efficiency Mode (green leaf icon)

Expected behavior

Background processes should not be aggressively throttled on a high-end desktop PC, and behavior should match the previous WebView2 version.

Attempted workarounds

• Power plan set to Best Performance: no effect
• Group Policy "Turn off Power Throttling": no effect
• Registry PowerThrottlingOff=1: no effect
• --disable-features=UseEcoQoSForBackgroundProcess flag: removed in Chrome ~Jan 2025

Additional context

The WebView2 folder at C:\Program Files (x86)\Microsoft\EdgeWebView\Application\ confirms 147.0.3912.86 was created today at 12:22 AM, coinciding exactly with when the issue began. Previous WebView2 versions did not exhibit this behavior.