CPU usage so sluggish via CLI SDK 4core codespace is unusable

[petrroll]

Describe the bug

Trying to run multiple sessions via CLI SDK (i.e. there's no UI) takes so much CPU 4 core codespaces stop being usable. See https://support.github.com/ticket/personal/0/4087041 if you can. If you can't let me quote the github support:

Copilot CLI is the biggest factor. During an active agent session it sustains ~60% CPU on a 4-core machine. Your snapshots show two Copilot CLI instances running simultaneously (one stale, one active), together consuming 80-90% CPU.

Avoid running multiple Copilot CLI sessions at the same time if possible, as each one consumes significant CPU.

That's not a good look :)

Affected version

GitHub Copilot CLI 1.0.11.

Steps to reproduce the behavior

1. Create 4 core codespace on github
2. Start 2-3 sessions via e.g. python copilot CLI SDK (not super heavy sessions, no coding, just Q&A)
3. Observe codepsace being unusable due to the extension host timing out due to CPU starvation

Expected behavior

at least if there's no UI, the overhead of copilot app is negligible. Especially when not searching FS for code or doing diffs, it should be super light.

Additional context

• 4 core linux codespace on github