Vscode extension debugging performance

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

Use cursor to launch a extension host and debug extension code is extreamly slow when doing step operations. when the stepping is stucked , still not fixed at version 2.4.7.

Steps to Reproduce

as reported in https://forum.cursor.com/t/vscode-extension-debugging-extreamly-slow/

Expected Behavior

same performace as vscode.

Operating System

Windows 10/11

Current Cursor Version (Menu → About Cursor → Copy)

Version: 2.4.7 (user setup)
VSCode Version: 1.105.1
Commit: ca0f9bf806f235ea014a22712cbcbf5e88ca77e0
Date: 2026-01-20T20:52:38.077Z
Build Type: Stable
Release Track: Default
Electron: 39.2.7
Chromium: 142.0.7444.235
Node.js: 22.21.1
V8: 14.2.231.21-electron.0
OS: Windows_NT x64 10.0.19045

Does this stop you from using Cursor

Yes - Cursor is unusable

Hey, thanks for the report. I see the issue didn’t go away after updating the VSCode base to 1.105.1. It’s a bummer the promised fix didn’t work.

The team knows about some general Extension Host issues, but we need a bit more info to tell if this is the same problem or a separate debugging case.

Could you share:

  1. Which extension are you debugging, or does this happen with any extension project?
  2. CTRL + Shift + PDeveloper: Open Process Explorer
    Please send a screenshot from when stepping starts lagging.
  3. SettingsApplicationExperimental → enable Extension Monitor Enabled, then CTRL + Shift + PDeveloper: Open Extension Monitor
    What does it show during debugging?

For now, you can try this workaround:

  • Close as many other extensions as possible before starting the Extension Host
  • Go to SettingsApplicationExperimental, search for anything related to the Extension Host, and try toggling it

Let me know what the logs show. It’ll help us confirm if this is specific to the debugging workflow or a general Extension Host issue.

Thanks for your response,

  1. I am developing a commercial extension, but it happens with all extensions on my side.
  2. it seems the monitor doesn’t show any high cpu/mem usage.
  3. nothing seems suspicious.

The screenshot shows the debugging of ‘cline’, when the breakpoint is hit , variables view takes a long time to refresh.

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