This is an update since yesterday. I’ve now tested 446.14 again and there was not a massive increase in fps in VR an pretty much the same stutters overall, therefore, I’ve reverted back to 457.30 (HAGS OFF, Game Mode OFF - I’ll need to make a few more flight with both ON and compare again)
However I’ve further tested out different situations with Gauge Refresh HIGH and in general I get smoother, albeit slightly lower, fps. Everything for now is pointing to the EFIS screens refreshing once in a while in burst, and when they do, they take so much CPU the render is skipping frames and causing stutters. However when set to HIGH there are more or less constantly updating and although they are taking more CPU per sec on average (more frequent updates) the renderer is more constant in presenting its views to the HMD (this resemble the pattern I’ve posted above).
All my tests are indicating there is a direct relation to the EFIS rendering resolution to the overall stutters. Furthermore the EFIS screen resolution depends on the Post Process resolution (the SteamVR SS value) and not on the Render Scale resolution (the TAA Render Scale value) I believe this is a bug in VR. In effect, in 2D it seems to depend on the TAA Render Scale only. This means for now you only get two choices:
- Lower EFIS rendering resources to increase fps.
use TAA < 100% and SS > 100% giving good scenery/cockpit with blurriness on the EFIS. - Crispier EFIS rendering visuals.
use TAA = 100% and SS <= 100% giving sharp EFIS drawings but blurry scenery/cockpit.
I’m even wondering if Coherant GT rendering (EFIS) is really hardware accelerated. In effect, when it is updating in burst the most affected graph is the CPU. This could mean the CPU is busy drawing the texture which will get updated to the video card, otherwise it is hardware accelerated and rendering on the video card but in this case I’m wondering why is the CPU is so much used when they are updating.
Please note in my flights where I was changing SteamVR SS and TAA Render Res I was trying to keep similar effective resolutions (close to 2K x 2K) but it is mostly when I was having the best EFIS legibility (TAA 100) I was having more stutters unless reducing SteamVR SS so much.
As a matter of fact, today I’ve tried pushing this further: SteamVR SS 200% and TAA 70% (or 60% depending). I can tell you outside view was stunning with lots of details, and the 200/60 combo was still giving me enough legibility (just at the limit when using 60%) flying over EDDF in the A320.
Nevertheless there was really not much stutters and it was overall a good experience fps wise. This is to me confirming the EFIS drawing technology is really taxing the resource much more than expected and the more you can reduce their impact the better.