GitHub Copilot app UI freezes with many persistent Copilot CLI processes and high memory use

[karelz]

GitHub Copilot app UI operations take 10-25 seconds while dozens of Copilot CLI processes consume about 15 GB of private memory.

Affected version or release

• GitHub Copilot app: 1.1.15
• Copilot CLI: 1.0.83-5

Installation context

Local GitHub Copilot desktop app on Windows 11 Enterprise, build 26200, with 31.6 GB RAM. This is not tied to one repository or organization.

What happened?

The app became nearly unusable after being open for about 11 hours. Local UI actions stalled even when they did not require an AI response:

• Opening a session context menu to rename it took more than 10 seconds.
• Typing frequently paused for several seconds.
• Switching between existing sessions took 25 seconds.

At capture time, Windows reported 94.6% RAM use and 5.16 GB page-file use. There were 45 copilot.exe processes even though only a few (~10) sessions were being actively used. Together they used 9.53 GB working set and 14.77 GB private memory. Some processes had remained alive for the full 10.9-hour app lifetime. The app listed 64 saved sessions in total.

The high process count and memory pressure appear to cause Windows paging and the UI freezes. It is unclear whether inactive sessions remain running or whether child processes are not cleaned up.

Steps to reproduce

1. Start GitHub Copilot app on Windows.
2. Use several sessions over the course of the day.
3. Leave the app running for several hours.
4. Switch between sessions, type in the composer, or open a session context menu.
5. Observe multi-second UI freezes and a growing number of copilot.exe processes.

Updated situation

1. In the same app instance after 1h+, all sessions are done (I have few dozens active sessions, but idle at the moment).
2. I started a new session - simple web search.
3. I switched to another session with results from earlier -- it took 8s to switch.
   • This is sign of something really bad happening, not me overloading the machine IMHO.

Expected behavior

Inactive sessions should not retain enough processes and memory to exhaust system RAM. Session switching, typing, and context menus should remain responsive regardless of the number of saved sessions.

Additional context

Diagnostic snapshot taken at 2026-09-06 12:48 CEST:

Process	Count	Working set	Private memory
copilot.exe	45	9.53 GB	14.77 GB
msedgewebview2.exe	46	3.35 GB	4.71 GB
node.exe	43	1.98 GB	3.33 GB
git.exe	62	0.67 GB	2.81 GB

System memory:

• Total RAM: 31.6 GB
• Free RAM: 1.7 GB
• RAM used: 94.6%
• Page file used: 5.16 GB
• Page file allocated: 40 GB

Earlier in the same incident, free RAM reached 0.6 GB and total RAM use reached 98.1%. No error dialog was shown.

I am willing to run a profiler, collect process dumps or traces, or perform other targeted investigation while the issue is reproducible. I am an internal Microsoft employee, if that is useful for reaching out through internal channels.

Related reports

• [Bugs] leaks memory by accumulating copilot.exe worker processes that are never reaped #1543 reports the same general class of unreaped copilot.exe workers on older app versions.
• Copilot App leaks CLI --server --stdio hosts after completed session shutdown #2303 was marked fixed in v1.1.15, but this incident occurred on v1.1.15 and may represent a regression or a remaining process-lifecycle path.