RTX 3080 in eGPU performs worse than RTX 3070 Mobile in Nvidia Optimus in Manjaro

Long story short, it seems I can’t get my eGPU working properly. It’s connected with Thunderbult 3 > Thunderbolt 4 cable. Everything indicates the RTX 3080 10GB in the eGPU is in use, I’m using my 3 external monitors through it.
However it performs worse than my internal dedicated RTX3070 Mobile.

A small comparison table from testing Snowrunner running both Windows and Manjaro on same system. So far other games seem to indicate same.

OS GPU 1920 x 1080 3440 x 1440 (ultrawide)
Win 10 RTX 3070 (dGPU) 70 - 85 FPS 40 - 55 FPS
Win 10 RTX 3080 (eGPU) 90 - 110 FPS 60 - 75 FPS
Manjaro RTX 3070 (dGPU) 65 - 85 FPS 35 -45 FPS
Manjaro RTX 3080 (eGPU) 25 -45 FPS 25 - 45 FPS

Both nvidia-smi and system monitor report RTX 3080 being in use. A lot of debugging and system info I have in Manjaro forums (Issue with eGPU performance (Gaming) on KDE - Gaming - Manjaro Linux Forum) but the guy helping me out there ran out of ideas so I’m hoping maybe somebody here has any hints on what I should troublsheet next or is it even an Nvidia Driver issue on linux?