The values under Control Panel\Desktop
HungAppTimeout (ms)
how long Windows treats a busy app as “busy” before calling it hung — stock
5000WaitToKillAppTimeout (ms)
how long logoff waits for a hung app to release — stock
5000What changing them feels like
Halving both (a common tweak) shows up at exactly one moment: sign-out/restart with an application stuck in a dialog — the wait floor determines how annoying “close programs first” is. The risk profile is the mirror: an editor with unsaved changes that was going to beep at you in 4 s gets murdered a second earlier.
What it won't touch
- Perceived speed of a desktop doing nothing special — the values sleep until sign-out.
- Slow app launches; nothing about them gates open-time.
- Structured-crash dialogs (WER dialogs have their own timers).
The tuning stance: set both to a deliberately documented lower value, log the before-image, and — most of all — know that two-second gain only ever matters when something else has already gone wrong.
ProofTune ProjectEngineering notes — every claim here names the bytes a real tool touches. Verify first, install second.