Apparently #macOS 26 has a bug that leads to massive CPU usage and lagginess in apps until you terminate and restart them. The lagginess creeps in over time, until the affected app is restarted again.

https://github.com/zed-industries/zed/issues/33182#issuecomment-3289846957

I ran into this with #iTerm2 but the issue has been reported already months ago in macOS betas with various apps.

Workaround is to: defaults write -g NSAutoFillHeuristicControllerEnabled -bool false

You will lose some autofill functionality by doing this, but apps slowing down over time is quite annoying, too.

#Apple quality control leaves things to be desired yet again.