One thing to look out for if anyone's using `stat fps` or `stat unit` to check performance: I'm seeing a big performance drop if any Unreal debug text is on screen (`stat fps`, `stat unit`, Blueprint messages, etc.). (UE 4.26.2, Wave SDK 4.4.0, Focus 3 firmware 3.0.999.418).
Scenes that get 90fps with no text on screen can drop to ~70fps (looks like it's doing 11ms, 22ms, 11ms, 22ms, etc.) by having Unreal debug messages on screen - I was just assuming they'd have a negligible performance impact, but it seems they don't. Only the very lightest (GPU wise) scenes can handle having any Unreal debug text and maintain 90fps.
Also, this was a big help (as expected) - thanks for the tip:
vr.PixelDensity 0.8