Bug Report Low fps with windowed game that NOT has the focus

koala

Active Member
I encountered a strange issue with low fps in a windowed game on my new PC.

I started a freshly installed OBS studio and added a monitor capture source. Then I started a game in windowed mode (Guild Wars) on that monitor. No start of recording or streaming, just preview in OBS. Now the issue:

- as long as the game does NOT have the focus, it has about 120 fps.
- as soon as the game gets the focus, its fps drop down to about 17!
- if I click on the desktop, the game loses focus. Its fps immediately resumes to about 120. If I click on the game again to activate it, its fps again drop to 17.
- as soon as I stop OBS studio, the game fps is permanently at 120 fps.
- if I switch the game to fullscreen while OBS studio is running, fps of the game is always at 120 fps
- if I remove the monitor capture source and add a game capture source for the game instead, there is no fps drop on focus change or if the game is windowed or fullscreen. Its fps is always at 120.

So I assume there exists some issue with monitor capture.

System:
- i7-6700k
- GTX 1070 with current drivers (downloaded&installed 3 days ago)
- G-Sync capable 144 Hz monitor with G-Sync active in windowed and fullscreen mode
- an second monitor is connected via DVI to the GTX 1070, but the game is displayed on the other monitor.
- Windows 10
- OBS studio 0.15.2
- Game: Guild Wars (not Guild Wars 2)

For fps display I used a Guild Wars command line option that makes the game display the fps number, so I assume it's pretty accurate.

I attach 4 logs, because I restarted OBS a few times. The first 3 contains my sessions with monitor capture, the last one contains the switch to game capture.
 

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mccor013

New Member
Same problem here. I am using a 2 PC LAN Stream Setup using Nginx.
Specs:
GPU: GTX 1080
CPU: intel 6900k 8-core
RAM : 64 GB DDR4
Mobo: Asus Deluxe 2

Running Overwatch (Game Capture via Fullscreen and Borderless Window) at 1440p 60 FPS @ 50k bitrate using the NVenc Encoder.

My issue is that OBS Studio runs perfectly fine at 60 FPS as long as anything BUT the game is in focus. The game itself has no FPS drop no matter what, but when I focus or tab back into the game, the OBS Studio preview (and the local stream its producing to the 2nd pc) lowers it's FPS dramatically around 10-15 fps.

My CPU usage never breaks 5%... ever. Is this a bug?
Oddly enough, when I run Overwatch in Window Capture OBS Preview drops down to about 45 FPS... and back up to 60 when changing focus away from the game. Anyone know whats going on?
 
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