Question / Help Garry's Mod Stuttering/Freezing/Choppy When Capturing With OBS

[GT500]

When I'm playing Garry's Mod and streaming with OBS (using Game Capture) I have a ton of performance issues. The game is choppy, and turning left/right is considerably slowed down, however the framerate can be over 100fps when this is happening.

If I alt-tab out of game, stop streaming, switch to Windows Classic theme to disable Aero, set OBS for Fullscreen Capture instead of Game Capture, and start streaming again then most of the issues go away and the game is playable.

I'm using 64-bit OBS, and here's a link to my system specs.

I tried exiting all security software (services are stopped), then restarting Garry's Mod and OBS, but that did not help.

I do have SweetFX installed for Garry's Mod, but my understanding is that OBS shouldn't be able to capture that in Game Capture mode.

 

[GT500]

Interesting... I removed the SweetFX files from the Garry's Mod folders, and it resolved the issue. I wasn't aware that OBS had issues with SweetFX.

 

[GT500]

The performance issues (stuttering/choppiness) were back yesterday, and I hadn't made any changes since removing SweetFX. This implies that SweetFX was most likely not the cause, but what could cause such an issue intermittently like that?