CODM: severe lag spike after Alt-Tab — TAC vendor regression

While playing CODM through TAC, the game runs smoothly — until the user Alt-Tabs out (e.g., to check Discord, change a Spotify track, glance at a browser). When refocusing back to CODM, the framerate drops to single digits and stays there for the rest of the match. Restarting the match doesn't help; only restarting the emulator restores normal FPS.

  • "somehow im not lagging anymore but if i tab holy lag" — Dusk
  • "The game had that issue since just before old GameLoop got obsolete. Another bug in the books lads" — ӃryptønPsychø (vendor-acknowledged but not fixed)

Root cause: TAC's renderer doesn't properly resume after losing window focus on Windows 10/11 with high-refresh monitors. Frame pacing breaks and the game effectively renders one frame per second of compositor wakeup.

Last updated 1 week ago0 users reported this issue2
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Solutions

solution #575

Run the emulator in borderless windowed mode instead of fullscreen. Borderless mode keeps the emulator's renderer active even when focus moves to another window:

  1. Click the 4-squares emulator menu → Settings → Display.
  2. Set Display mode to Borderless Windowed (NOT fullscreen).
  3. Apply, restart emulator.

solution #576

Don't Alt-Tab during a match. If S1 doesn't help, the practical workaround is behavioural: open Discord / Spotify / browser BEFORE queueing into a match. Once the match starts, treat the CODM window as exclusive — use overlay shortcuts (Discord push-to-talk, Spotify global hotkeys) without switching focus.

solution #577

Disable Windows Game Mode. Game Mode aggressively de-prioritises background apps after focus loss, including TAC's renderer threads. Settings → Gaming → Game Mode → toggle off.

solution #578

Switch Windows power plan to High Performance. On Balanced power plan, Windows aggressively throttles GPU clocks when a window loses focus. High Performance keeps GPU at peak clocks regardless: Settings → System → Power → Power mode → Best Performance.

solution #579

Acknowledge: this is an unfixed TAC bug carried over from old GameLoop. Per ӃryptønPsychø, the bug has existed since pre-2026 and there's no announced timeline to fix. The mitigations above reduce frequency but don't eliminate it.

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