Update OBS Studio and StreamFX often!
Many of the performance problems that get reported often come from using outdated or even ancient versions of OBS Studio and the plugin. Updating to a more recent version of both usually instantly resolves these due to newer versions having received more optimizations.
Reduce SDF Effects Texture Size
Dynamic generation of Signed Distance Fields (furthermore called SDF) is incredibly expensive, with a single SDF Effects filter on a 512×512 source taking as much resources as a Box Area Blur at 64px width. The impact of it though can be reduced by checking the Advanced Options property and then reducing the SDF Texture Scale.
Most sources look fine with the SDF texture scale set at 12.5%, others might need a little more, but almost nothing actually requires a 100% sized SDF texture. Which scale setting you end up using is up to you, but beware of scaling artifacts.
Avoid duplicating Sources
While this is technically advice for anyone using OBS Studio, it also applies to StreamFX. Many of your filter graphs will probably have some overlapping elements, and you can drastically reduce the rendering impact by reusing results.
For example if you have a Video Capture Device source with Chroma/Color Key and Color Grading, and want to have two different filters going from there, it is a better option to use Source Mirror to mirror the source. Especially for costly filters, such as Blur and SDF Effects, this is a very efficient way to solve a performance problem.
And that’s it. When you apply all the fixes mentioned here you should see a decrease in GPU usage, which for some may be massive, while for others it might be very small. But even a small GPU usage decrease can allow you to hit a slightly higher framerate target. Maybe with this you’ll be able to go from 30 to 60 fps, or go from 720p to 1080p.
In my case switching out a few of the blurs with Dual-Filtering allowed me to record and stream at 1440p144 instead of 1440p30, which means that I’ve more than tripled the available GPU time just with a single fix.
So what are you waiting for? Delve into your scene setup and look for things that you can optimize!