INDEX worked fine, NOW.... Very bad

You might want to try out some community mods specifically for the propellers:

I’m going to mess around again with motion smoothing tonight, and possibly the prop mods, but I will say that I’ve had acceptable performance without the prop distortion and minimal judder (at least not terribly noticeable to me) just relying on async. reprojection with motion smoothing disabled.

Ok this thread blew up overnight.

I’ll add in my metric to this issue - I hadn’t paid attention to “beta” status or not but folks referencing it here caused me to think/check.

I found that my system had apparently reverted itself OUT of the “beta” program for SteamVR. Reactivating the beta 100% solved the odd stutters I was seeing.


Hi @CptLucky8 ,

I finally had a chance to try this out this morning, given that the Azure servers were down last night. Very interesting… jury is still out somewhat.

This is similar to my previous configuration, with these differences. I was previously running TAA 70 + SS 224, no Motion Smoothing, Fixed rate 30fps, 0 prediction.

My first impression was that this was slightly blurrier than my previous config, and aliasing was more noticeable on straight edges. But as soon as I started flying I have to say I was impressed by how smooth it was and I think the outside terrain actually looked slightly better. The overall experience was definitely smoother than I am used to - almost “butter” smooth, and I can’t say that the cockpit was blurrier to where it turned me off - certainly readable. I’m definitely going to live with this for awhile. MSFS is an incredible experience in VR when it is as smooth a silk!

I also will note that the artifacts from motion smoothing seemed much less pronounced and annoying than when I had tried it before. And this is in the C172 steamguage model without a prop mod of any kind. Possibly something to do with one of the latest SteamVR beta updates?

My only major concern is that I experienced a CTD after a few minutes over Washington DC, something that I rarely have happen. I’m hoping it was a one time random event. But overall I think this config might be a winner.

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Thank you for sharing your experience!

The artefact are vastly reduced on my test system thanks to the prediction setting in ms. There is a very good technical explanation in “My VR Settings - Index” topic about this one.

In practice, I find the easiest it dialing in the fixed rate which seems to be working best first, then adjusting the prediction to where the artefacts are minimal. I turns out I end up nearly always at 25ms with the latest SteamVR beta.

Sometimes you might find you can get a little higher than 24fps rate but maybe not up to 30fps. In this case you might want to explore 144Hz which gives you different rate options.

The hardest is deciding whether you fly with or without motion smoothing. Sometimes it works fine without and you can raise the resolution, sometime it works better with and you can eliminate juddering. I’m not settled on any but the next advantage of the Index vs the G2, is you can chance this live, on the fly, and immediately compare. You don’t even need a controller thanks to the button on the Index!

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What I find interesting with this new configuration is that 24fps with motion smoothing feels smoother than 30fps without. I wasn’t experiencing stuttering before, but I could see framerate drops in certain areas which so far do not seem as noticeable now.


Flying over the Aleutians in the xCub, I am now smooth with no headache. I have HAGS turned off, SteamVR BETA 1.16.7. What should I adjust and what is the MAX that I should go to get a more clear picture thru my INDEX. Still seems too blurred!

Well CptLucky, here’s a new one for ya! I’m on the tarmac at KSAN, sitting in the A32NX. I load up a SIMBRIEF plan into the FMC, get everything ready to go. Activate VR with CTRL-TAB. And it’s smooth. BUT… As soon as I hit the SPACE BAR to recenter my seat view, the frame rates tank, jitters and a total mess. I did this 3 times and every time I hit that space bar, the VR experience goes to ■■■■. Any ideas?

Wait for the next update? :grinning:

Honestly how could I know?! You might be having the dreaded mouse bug:
Mouse cursor bug that lowers FPS - Virtual Reality (VR) / General - Microsoft Flight Simulator Forums

The thing is that until you depress the space bar, any input is disabled, therefore, the code is not “scanning” (polling) any interactive item (lever, button, etc…). The bug described above is related: when hovering the mouse on a UI element, the code knows you won’t interact with the cockpit and simply doesn’t poll the items until the mouse leaves the UI. Good optimization idea in general, but poorly reflecting on performance in practice, because it shows polling all interactive items in the cockpit is really taking a lot of CPU power and this makes me wondering why so much.

Is this CoherentGT, meant for UI mostly, which when used for interactive and EFIS display (good idea - one size fits all - but not designed for real time display in a game in my opinion when competing with so many other things to display at the same time) is causing this because instead of traversing a node tree in 3D using traditional BSP-like techniques, it forces to traverse nodes serially for example?

Is this just because they are using mutex while traversing the nodes?

I really don’t know, but you can see with XP11 (if you’re not a developer doing 3D code and apps), traversing the entire list of interactive items in a 3D cockpit, with the additional highlighting in green of the same 3D cockpit item when the controller is touching it, doesn’t take this much CPU resources at all. It would require maybe half a million of these items in a cockpit to start feeling the CPU struggling given the power available in our modern CPUs.

This is not a rant, I’m just trying to explain probable causes as seen with the eye of a developer.

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