Porsche CUP GTR 992 MOD Issue

Hi I just bought MOD Porsche Cup 992.

In every other car or Mod i can play it on Hight settings ana have usually 120-160 FPS in game with 23 cars on track.
On Porsche Cup Mod it takes an eternity to load (sometimes 5/6 minutes) and when i go to track it gets 5-6 FPS the it goes up to 150 FPS but it jumps to 40 / 57 / 120 FPS and have lots of stuttering.
If i leave track it gets stuck again on loading times to get to main menu.

If i setup the session alone it is normal.

 

Maybe deleting the 992, verifying all files/ data via Steam check and reloading the 992 could help