GPU thread taking up 20-30 ms for no reason?

So, I’ve recently started profiling my game and it appeared at first that I had a huge CPU overhead. When I dug a little deeper it turned out that the majority of the CPU time was “CPU Stall - Wait for Event” , and that the GPU was actually the culprit.

For some inexplicable reason, I will occasionally get a good 20-30ms of GPU time for no reason that I can tell. Heck, I’ll even get it in a blank map with nothing in it at all. I tried opening up the GPU profiler tool to see what the issue might be, but it only reports 5 or 6 ms of GPU time at best.

At other times my GPU time is normal (hovering around 8 ms in a fairly empty map and about 15 in a highly detailed one).

So what gives?

I’m on a GTX 980 card, so you would think it wouldn’t be having much trouble here. Almost seems like a driver issue? ( i’m on the latest from Nvidia )

are you running with -dx12 or -d3d12 ?

I 't believe so? as far as I’m aware I’m running in the native Dx11

Ha! Ok, I think I may have found the issue. I had the material editor open on my second monitor and the ‘live preview’ feature was active. Even just having a complex material open at all while doing PIE appears to bottleneck my GPU

It actually does appear to be the case when I have any secondary windows open in the editor while running PIE. It can be the particle editor, or a blueprint, or the material editor. It just kills my frame rate regardless.

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