Frame drops only on certain spots, and only in VR (ex: LFPE 25R)


I have huge frame drops only facing certain areas, ex from LFPE 25R, while looking to the West it drops to 8-11FPS with APP GPU rendering > 120ms. I also hear coil whine.

While turning the head on other sides, over 36FPS without any issues, APP GPU RENDERING is correct.
Indeed that area does not contain particular buildings, shapes,… mostly fields, trees, small towns…
It’s very strange because it’s only happening when I’m looking to the west from that spot…

Those frames drops are not while playing 2D without VR, it only occurs in VR with either SteamVR or Oculus LINK

What I did test:

  • SteamVR // Oculus link = same
  • different nvidia drivers = same
  • changing weather = same
  • different time of the day = same
  • hiding other players = same
  • all settings very low / no SS / in SteamVR / Oculus Tray / in game = same
  • other aircraft = same

Oculus Quest 2 + official USB cable + RTX 3080 + 32GB + Ryzen 9 3900X + 970 EVO SSD

I just recorded here: Flight Simulator VR Framedrops (particular spot) LFPE 25R! - YouTube
Usually I have smooth 36FPS (from 1min22), flying mostly in East side of France, I didn’t notice such issues before.

Could someone please try this spot as well? Thank you very much

Thank you for sharing this video with the sensors!!

I might be wrong but when looking at the sensors readings it seems to indicate exactly the correlation with this problem most prominent since WU3 but which was always there to get started: Bus Load.

In other words (and if I’m not mistaken) the rendering loop is stalling because the game is suddenly updating/discarding lots of buffers, and I believe these are vertex buffers for the most part (you can search my posts in the forums with “buffer” as a keyword for all my comments throughout).

One thing I’d suggest when this is happening is to cross check whether it is direction related or not, and to do so:

  • enter slew mode Y
  • rotate 90 deg CW NUMPAD 3
  • exit slew mode Y
  • compare looking left, front, right
  • repeat 2 times more for full circle.


  • if you spot it is always looking in the same cardinal direction (say North), try to look at the type of scenery items there are

  • if you spot is is always looking in the same aircraft direction (say left window), then we’ll have to dig deeper.

  • if you spot is is not direction related, then I believe it is a bug in the rendering engine and the DX11 buffers rooted deep at the core of the basic rendering engine code.

All this will be good material to tell Asobo.

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