The error [composer] Extension host became UNRESPONSIVE produces a lag for a few seconds and makes editor unresponsive

[udaaff]

Where does the bug appear (feature/product)?

Cursor IDE

Describe the Bug

A lot of errors in the console that affects code editor and make it unresponsive for some seconds!:
16:28:29.364 workbench.desktop.main.js:5606 [composer] Extension host became UNRESPONSIVE undefined {arch: ‘x64’, platform: ‘win32’, channel: ‘stable’, client_version: ‘2.0.77’, extensionHostKind: ‘LocalProcess’, …}activeComposersCount: 3arch: "x64"channel: "stable"client_version: "2.0.77"extensionHostKind: "LocalProcess"extensionHosts: platform: "win32"timestamp: 1763735309364[[Prototype]]: Object
error @ workbench.desktop.main.js:5606
(anonymous) @ workbench.desktop.main.js:2738
await in (anonymous)
(anonymous) @ workbench.desktop.main.js:2738
_deliver @ workbench.desktop.main.js:49
fire @ workbench.desktop.main.js:49
(anonymous) @ workbench.desktop.main.js:7494
_deliver @ workbench.desktop.main.js:49
fire @ workbench.desktop.main.js:49
(anonymous) @ workbench.desktop.main.js:492
_deliver @ workbench.desktop.main.js:49
fire @ workbench.desktop.main.js:49
_setResponsiveState @ workbench.desktop.main.js:492
_checkUnresponsive @ workbench.desktop.main.js:492
(anonymous) @ workbench.desktop.main.js:492
doRun @ workbench.desktop.main.js:50
onTimeout @ workbench.desktop.main.js:50
setTimeout
e.setTimeout @ workbench.desktop.main.js:5057
schedule @ workbench.desktop.main.js:50
_checkUnresponsive @ workbench.desktop.main.js:492
(anonymous) @ workbench.desktop.main.js:492
doRun @ workbench.desktop.main.js:50
onTimeout @ workbench.desktop.main.js:50
setTimeout
e.setTimeout @ workbench.desktop.main.js:5057
schedule @ workbench.desktop.main.js:50
_checkUnresponsive @ workbench.desktop.main.js:492
(anonymous) @ workbench.desktop.main.js:492
doRun @ workbench.desktop.main.js:50
onTimeout @ workbench.desktop.main.js:50
setTimeout
e.setTimeout @ workbench.desktop.main.js:5057
schedule @ workbench.desktop.main.js:50
_onWillSendRequest @ workbench.desktop.main.js:492
_remoteCall @ workbench.desktop.main.js:492
s..r.charCodeAt.s. @ workbench.desktop.main.js:492
n @ workbench.desktop.main.js:4989
distribution @ workbench.desktop.main.js:546
checkFeatureGate @ workbench.desktop.main.js:589
cd @ workbench.desktop.main.js:589
isUnificationEnabled @ workbench.desktop.main.js:5638
handleGlobalMouseMove @ workbench.desktop.main.js:5638
(anonymous) @ workbench.desktop.main.js:5638

Steps to Reproduce

no steps. the mistake appear while i’m editing code.

Expected Behavior

No lags while editing code.

Operating System

Windows 10/11

Current Cursor Version (Menu → About Cursor → Copy)

Version: 2.0.77 (user setup)
VSCode Version: 1.99.3
Commit: ba90f2f88e4911312761abab9492c42442117cf0
Date: 2025-11-13T23:10:43.113Z
Electron: 37.7.0
Chromium: 138.0.7204.251
Node.js: 22.20.0
V8: 13.8.258.32-electron.0
OS: Windows_NT x64 10.0.26200

Does this stop you from using Cursor

Sometimes - I can sometimes use Cursor

[deanrie]

Hey, thanks for the report. Extension host freezes are often related to extensions, network issues, or corrupted storage.

Let’s collect some diagnostics:

Please share:

• Extensions check: Ctrl+Shift+P → type “Developer: Open Extension Monitor” → take a screenshot during a freeze
• Process info: during a lag, press Ctrl+Shift+P → “Developer: Open Process Explorer” → screenshot showing CPU/memory usage

Quick things to try:

• Test without extensions: run cursor --disable-extensions from the command line to check if extensions are causing the lag
• Clear storage: close Cursor → go to %APPDATA%\Cursor\User\globalStorage\ → rename state.vscdb and state.vscdb.backup → start Cursor again

Note: your log shows activeComposersCount: 3. Having multiple agents/models running at the same time can also make freezes worse.