Performance regression with Steam Proton on Nvidia only

The problem has described there:

About this problem in short:
FPS drop with skeleton revival animation in Elden Ring - game with Steam on Linux with Proton.
Setting a game launch options to:
VKD3D_CONFIG=no_upload_hvv %command%
fixes FPS drop on skeleton revival animation
but that make GPU usage on all game little higher about +2% for FullHD. For 4K i guess is more.
But without this command we got a great FPS drop during skeletal revival animations.
And that is happen only on Nvidia, not on AMD.
So i guess there can be a fix in the driver to prevent FPS drop on skeletons and prevent higher GPU usage in same time.

A video when running normally the game:

And with fix VKD3D_CONFIG=no_upload_hvv %command%

According to the Proton issue report, this seems to be a dGPU/BAR specific issue, not nvidia specific.

I understand. So the dev’s of the game need to fix this.

Yes, as it lays out to me the game’s engine is using excessive BAR-transfers to video memory for that effect so it slows down the gpu to a crawl. The workaround is to prevent those transfers for the whole game and use system memory instead which is slower, thus slowing down the whole game. Seems there’s only the decision which toad to swallow.
Integrated gpus like on the steamdeck are not affected since they use system memory for the gpu anyway so no BAR-transfers are needed for memory access.