Low FPS sometimes

I got this strange problem for some time now.  Normally Im running AMS at 120 FPS.  Sometimes  after  quitting the game and restarting
again the FPS drop to around 30 FPS. I have to reboot the PC to get  120 FPS again.  Anyone come across problem like this?

Can't say that I have, but it looks like the 2nd time you start AMS it doesn't start with the same graphical settings. In graphical options in game check if you don't have an FPS limiter set. I run AMS with anything between 300 and 550FPS depending on grid and track so why not.

The fact that you get exactly 30 FPS makes me think it's linked to an FPS limiter.

Fps limiter in video card setting maybe? If you have AMD check if it is in the "Global" setting, I turned it off here and use in game as some (like LoL) I play at 120 and others at 60.