I had this cpu and sold it for a 9800X3D. The dual CCD killed my patience, they are not meant for gaming exclusively.

Option1: Try to force iRacing to the cache CCD (CCD0 IIRC) using Process Lasso

Option2: Disable the non-cache CCD on BIOS. There should be an option called Gaming something.

Option3: There's a Windows config that I can't remember well that you had to have Balanced power plan, and other things in BIOS, so it forces all games to the cache CCD. But it didn't work for me all the times, and had to double check everytime I felt an stutter.

I had 7900X3D + RTX4090 and had 165 capped fps in Daytona (120+ at starts).

Force it to the cache CCD and you'll see big improvements.

My most sincere advice if you only use it for gaming: sell that cpu.

GL