FPS increase in games after ALT+TAB

Hi, first post and wanted to say thank you for all the great info on this site, very awesome!

I have a minor issue right now, not even, more a curiosity. I tested this in multiple games and with different drivers:
For example in Apex legends, on a random spot inside shooting range I will get 260fps stable. I tab out of the game and back in, suddenly I get 290fps. This effect lasts 10-20 seconds after that I return to baseline 260fps. I can repeat and replicate this as often as I want and on any spot in the shooting range, doesn't matter.

I searched and found this very old thread
https://forums.guru3d.com/threads/what-is-alt-tab-problem-and-what-does-it-do.240317/

Apparantly back then there was a driver issue with Vram management, if I read that right. I checked my memory usage with MSI afterburner but it's constant and at around 1300 mb.

My specs:
1080ti
Xeon E3-1230
16gb DDR3
Windows 10, 1909
Ingame: Everything ultra low, no vsync, no fps cap etc.; turned off full screen optimizations.

Any ideas what's happening or any tests I could do? If you could try this out and tell me if you get the same effect(which game doesn't matter) that would be awesome!

 

I've only noticed something similar when running Unigine Valley benchmark in DX11, but has been that way as long as I can remember using Windows 10 (2015).

My first guess would be something related to the graphics API or Nvidia's driver in relation to the programs it happens with.

 

Thanks for sharing!
It's happening at least in both DX11 and vulkan games for me.

 

Oh dang, decent game though!

 

I had the same issue in GTA Online. When I get in the game I'd be locked at 48fps, but with a quick alt-tab I shoot up into the 80's. I also had the same problem in A Plague Tale Innocence recently, but switching from HDMI to Display Port fixed that issue. As for GTAO, who knows. I'm done with that garbage and it's uninstalled.

 

@jbscotchman
Are you saying this doesn't happen in your other games? I am using Display Port fwiw

Man I tried for a good hour again to find out what's happening. I looked if any service or process starts/ends, -nothing. Checked if any background process is changing CPU usage with process explorer -nothing.

What could possibly change in a 10 second window after tabbing into a fullscreen application?
-No process starts or ends
-No process alters CPU usage in any meaningful way
-What else?

Is there any monitoring tools for GPU, something like afterburner, but more in depht?
Edit: Another question I had in mind to ask. When you tab out of a game, does the Vram get cleared?

 

I'd say it's a priority boost most likely (windows scheduling). Can you check your win32seperation value?

 

Yes. It's very bizarre I know.

 

My value is 2

 

Set it to "background programs" and then "applications" again, that way it will set a different value which is in my experience better than the (installation) default.

 

Ahh thanks!
For people wondering Win32PrioritySeperation changed to 26 hex in: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\PriorityControl

Unfortunately it didn't resolve the problem.
I tried with another game(can't change priority in apex) and set priority to real-time in taskmanager just to see if it would change anything, but nope...
Also tried windowed mode -same effect.

Still not sure if it's just me or everyone that is affected....from the games I tested the effect can be less pronounced based on which game you play (30+- fps in apex vs 10+- in hyperscape).

 

I would not start changing registry settings. That's just gonna give you more problems down the road.

 

Nah the windows setting option changed the key....

 

game engines unload stuff from memory on tab switching, if performance increases its only because things that were in memory are currently unloaded and not being checked for culling.

 

@Astyanax
I bet you're right, though I know nothing about this stuff. Out of curiosity, what would happen if you programmed a game to unload the memory like that periodically every X seconds?

 

Maybe..

https://forums.guru3d.com/threads/standby-memory-reclaim-service-game-stuttering-fix.426671/

 

Interesting thread, how long are you alt-tabbing out of the game?

Just thinking out loud here, but it is possible that the video card is not sufficiently cooled (or has a low-quality cooler) whereby when alt-tabbing out, the temperature decreases significantly enough that when returning to the game you are entering back with higher core clock and memory speeds on the videocard, and thus a higher frame-rate. The GPU heats back quickly within 10 to 20 seconds and framerate drops to the regular level of your heated GPU.

 

That's the thought that came to my mind as well. It certainly seems plausible.

 

Nailed it! Don't know how I missed it, was using afterburner and didn't even think about temps....my processor is so old, I rarely get the GPU to max temp.
Thanks man, what a relief

 

I would like to share that i have 2 displays (My main in dp, and my second on HDMI) I switch my monitor over to my second and the fps problem was fixed! i put it back on my main and it just instantly when from around 300 back to being locked at 142. I think it is something with the monitor profile. Does everyone here, that has this problem, have NVIDIA control pannel for their graphics?