Gen-4 TAA GPU performance

Hello!

We are currently evaluating UE5. Our current branch is based of UE 5.5 branch as of about a month ago. Just for context, we use forward shading and are on OpenGLES 3.1, Vulkan disabled. In 4.27 we mainly used TAA (TAA when camera is still, FXAA during camera transitions). In UE5 we have been testing out the new Gen-4 TAA (which I believe is the desktop version?) and have seen a great increase in visual quality, however to the cost of quite a bit higher GPU usage. We spoke with Vince briefly during a visit and he mentioned that he may have some tweakable vars or other ways in order to improve performance without sacrificing too much of that increased visual quality.

On average, the GPU % is the following:

UE4.27 (TAA): Between 60%-73%

UE5.5 (Gen-4 TAA): Between 74%-88%

UE5.5 (FXAA): Between 56%-64%

We have the following set in terms of TAA cvars:

r.TemporalAA.Upsampling=True

r.TemporalAA.Quality=2

I can attach an Unreal Insights capture separately if needed. Any pointers here would be much appreciated!

Thank you!

Nevin

Spoke with Vince and he suggested the following Cvars:

r.TemporalAA.UseMobileConfig=1

r.TemporalAA.Mobile.UseCompute=0

r.TemporalAA.Upscaler=0

r.TemporalAA.Upsampling=0

r.TemporalAA.Quality=0

However, changing r.TemporalAA.Upsampling from 1 to 0 makes the render look very washed out:

[Image Removed]

This is what it looks like with all the other CVars set as above except r.TemporalAA.Upsampling kept at 1 (looks normal):

[Image Removed]

Nevin

Wow!! Quick update, I tried the above TAA settings as Vince suggested and it brought GPU load down by 15-20% while keeping about the same improved visuals.

Still seeing the washed-out render issue above if I change r.TemporalAA.Upsampling to 0 however.

Hi Nevin,

Glad to hear those settings helped! It should be fine to leave upsampling as it is, since it’s causing problems. We’re going to follow up with some testing to see if there’s potentially a bug here, but if you’re happy with your performance after setting the other CVars then we can go ahead and close this ticket out.

Best,

Cody

Hey Cody,

Ok sounds good, we will keep the upsampling as it is for now. This ticket can be closed.

Thanks,

Nevin