Multitaksing/Alt-Tabbing impacts your Gaming performance

[StellarDominus]

I have noticed a weird issue with Windows, where alt-tabbing from and into the games breaks the way the games work. I have been observing inconsistencies in input latency, bad frame pacing etc., regardless of "Fullscreen optimizations" disabled or enabled, which I thought was the culprit. Every game run just fine only until alt-tabbing out to the desktop or other applications and when alt-tabbed back, they start to suffer with frame pacing issues like judder, altered input latency and Double buffering Vsync being overridden with Triple buffering, things like that. Every game might look like running in fullscreen but, seems like they are actually not, but worse. Pressing Alt-Enter a couple of times or toggling in-game settings to fullscreen fixes it and sometimes, restarting is the only way. The game has to start in fullscreen (from scratch) by itself to run with pure performance. If navigated to other applications by minimizing or alt-tabbing or whatever the key combination, the game breaks its performance.

For instance, Grand Theft Auto V uses Double buffering Vsync, maintaining steady frame pacing, input latency, with no interruptions in the middle of the game like navigating to other applications. When alt-tabbed to any application and back into the game, the game might still look like it is running is normal fullscreen mode like before, but, the Vsync turns into Triple buffering mode and the frame pacing becomes terrible with input lag variation. Alt-Enter might fix the issue sometimes and sometimes not.

Maybe this is how the "Desktop Window Manager" in Windows handles applications and has trouble turning games back to the state, where they were before multitasking to other applications, without having to restart the whole game or toggle screen modes in game settings. Maybe games run in "Flip Mode Presentation" which is the new way Windows handles games in Borderless Fullscreen mode and cannot be fixed unless the behavior is modified by the developers. This might look like it isn't that much of a problem, but, it is already interfering with the actual gaming performance particularly who cares about consistent frametimes, latency and stuff.

I used a tool called "PresentMon" to monitor what is going on behind the scenes and the tool shows the latency being increased after alt-tabbing from the game and back into the game. You can refer to the picture, I attached.

What do you think could be the reason for this problem? A nice explanation will be appreciated. Thank you.

[Simon95]

Can you tell me how you did the test? I want to try the same.

[StellarDominus]

Can you tell me how you did the test? I want to try the same.

You can observe the feel of the game being different as soon as you alt-tab from it and back in. Notice the difference in input lag and frame pacing with Vsync on because, with off, it's hard to notice. It might actually feel like a placebo, but, I am sure you can notice it. It can be even easier, if you run the game at 30FPS (Half-refresh rate) in order to keenly observe the judder and frame pacing. In my case, I used a gamepad to pan the camera consistently.

What I did was downloading "PresentMon" tool and kept running it in the background which is being recorded with OBS, ran GTA V, and checked the latency before and after pressing alt-tab. By "Alt-Tab", I mean switching to other applications/desktop while the game is running. I don't know whether the stats are accurate, but, I did felt the difference. Vsync is also effected switching itself from Double buffering to Triple buffering. Have tested a few other games too, like Watch Dogs.

[MT_]

Two guys (including me) posted something similar with alt+tab and gsync/nvidia.

There is a bug somewhere and its not related to a windows build, but it looks like a new bug has slipped into one of the newer nvidia drivers.

Im wondering why this doesnt get much attention.

[StellarDominus]

Here is an other post with similar issue - viewtopic.php?t=6153

[TTT]

Maybe it is to do with Windows Full Screen Optimisation?

Disable it in the games .EXE but you won't get the fast Alt-Tab anymore, also some games force it on now even if you try to disable it in Windows.

[deama]

You can always try to disable dwm and see if that works with alt-tabbing.
You won't need to run in fullscreen exclusive mode anymore with the dwm disabled, but make sure to disable dwm after running the game, as it may not even run if you have winlogon.exe suspended.

Also, why is your presentmon.exe latency so high? Mine is usually at around 10.5ms, even with the dwm on.

[RamenRider]

Maybe it is to do with Windows Full Screen Optimisation?

Disable it in the games .EXE but you won't get the fast Alt-Tab anymore, also some games force it on now even if you try to disable it in Windows.

Disable Fullscreen Optimizations has been Broken since 1903. viewtopic.php?f=10&t=7168

But I added a tweak that can help in the last thread.

[LeRutY]

Oh my god, you don´t know how thankfully I am for someone to post this. I was really thinking it´s my PC which has that issue and I´m the only one. Has this been a topic on all OS or only on windows? I don´t really understand though how many people seemingly alt tab out of games (in youtube videos) and don´t get any of the said issues OR are not aware about the consequences of doing it. Alt tab (or pressing the windows key) basically kills the gaming experience, even worse after multiple times. I think it also depends on how powerful the hardware or demanding the games are

[Sirito]

Will a second monitor helps in this case as you don't need to alt tab or do you still need to alt tab to reach the cursor to second monitor?