Forza Horizon 5 finally working fine under Linux

Forza Horizon 5 running under Linux (openSUSE Tumbleweed KDE) using a PS5/Dualsense controller.
We are discussing this video over at reddit:
https://www.reddit.com/r/linux_gaming/comments/12w1vdi/finally_got_forza_horizon_5_running_well_amd/

Minor Linux tweaks:
– Enabled hugepages – https://www.reddit.com/r/linux_gaming/comments/uhfjyt/underrated_advice_for_improving_gaming/
– “Performance” and “Compute” power modes for CPU and GPU
– Kernel 6.2 is crashing the AMD GPU module. 6.3 seems to be OK. 6.1 is confirmed being ok.
Stock mesa (“video driver”) and Kernel.

Using Valve’s Proton. Version: Experimental – Bleeding Edge.
Launch option in steam: gamemoderun %command%
Upper option needs “gamemode” installed on the linux system.

Steam overlay is disabled.

Important Forza settings:
– “SSAO QUALITY” must be off as it causes artifacts!

Hardware:
CPU: Ryzen 5 5600x (-20 PBO / +200Mhz)
GPU: Radeon 6600xt (2700MHz / 2200MHz VRAM / -80mV)
GPU undervolt, overclock, custom fan curve, power profiles are set with corectrl (graphical interface tool)

BIOS tweaks:
– Personally I have disabled fTMP and HPET in BIOS (disabling them fixed stuttering issues on Windows machines), but doubt you need to bother with them.
– Resizable BAR/ SAM is on.

Here is how to enable AMD’s Smart Access Memory (Resizable bar) on Linux:

“Above 4G decoding” is Enabled in BIOS while “Re-bar”/”Resizable bar” is Disabled. We have found out that having both causes massive stutters with Gigabyte motherboards (maybe others too?). Having only “Above 4G Decoding” enabled provides a massive FPS boost with no stuttering. Having only “Above 4G Decoding” Enabled gives access to the whole memory BUS with no need for “Re-BAR” to be ON in BIOS. More discussed here: https://www.reddit.com/r/linux_gaming/comments/v58ts5/quick_heads_up_about_something_i_discovered/

NVIDIA seems to be OK with Proton 8 now.