So, I recently found regardless of my driver, or RHI I’m using in UE5, going from the background to focus puts a really high RHIT time, sometimes it goes away in a second and I’m back to 120fps, other times it stays for ten-fifteen minutes and leaves me at 5fps. GPU time and all other process times remain at a max of 2ms, but RHIT will hit 30ms, for no apparent reason. Unfortunately, I don’t have details of where it’s coming from, as the tools for debugging don’t seem to trace it. Here’s a screenshot of the stat unit in DX12 as it visibly separates RHIT and GPU.
The scene is by no means complex and this happens even in an entirely empty project. As you can see though in the screenshot, the actual render time from the gpu is almost exactly 3ms while my RHIT is 27ms. And this can persist for a very long time after giving the window focus before it suddenly fixes itself and drops almost instantly to 2-3ms.
My engine version is 5.2.1.