Demo 60fps but Ultimate edition 15-20fps

Hello I played FH 4 with xbox gamepass before and now after trying the demo again I bought ultimate edition. Although I got 55-60 fps with the xbox game pass long ago and getting 55-60fps with demo now, I am only getting 15-20 fps with the current version of FH4 Ultimate edition.

Footage are taken in the same hour with same pc: ( PC Specs: , windows 10 version 2004)
Demo 1080p Ultra settings 55-60 FPS: Forza Horizon 4 Demo Ultra 1080p - YouTube
Ultimate edition 1080p Ultra settings 15-20 FPS : Forza Horizon 4 Ultimate Ultra 1080p - YouTube
Ultimate edition 1024x768 very low settings 15-20 FPS : Forza Horizon 4 Ultimate very low 1024x768 - YouTube

It seems that current version of the game locking me to same FPS interval for some reason although I tried to lock fps to 30-60 or unlimited with vsync off result was same.

While FH4 Demo is version 1.19** Ultimate edition is 1.4*** .

I used DDU in safe mode to uninstall graphics drivers and reinstall the latest version didn’t fix.
Tried changing pagefile to 3072-20000 to increase pagefile didnt fix.
Tried changing app settings in nvidia control panel and set to maximum power didn’t fix.
Tried re-installing the game didn’t fix.
Tried disabling second monitor didn’t fix.
Finally I said f it and did a fresh install of windows, didn’t fix.

Although problem seems to be rooted at game version I would like to ask for other possible fixes to give my last attempts. Thanks for the time and help.

EDIT: Fixed by completely removing softether vpn from my pc . Apparently disables ikeext which is important for forza game. credit to @kruglove

Have a look at this thread, there have been some other people who have got very low fps on perfectly capable machines.

Have you run the in-game benchmark to see whether it is your CPU or GPU which isn’t being properly utilised.

literally the first on that page fixed it thanks so much.
It was the stupid softether which I used my machine as vpn server. Pretty weird that it doesnt allow another service to run.