Hello guys, I was able to solve my problem. It's not anticheat that causes the stuttering. It's due to AuraSync from Asus (Amoury Crate). But it's not the program itself but selected lighting modes that cause the stuttering. Whenever you don't select a static lighting mode stuttering occurs. You have to set your RGB lighting (for me it is an ASUS ROGStrike 4080) to static RGB lighting. No flashing color profiles. For example if you switch off AuraSync and only use a fixed color profile the error goes away. If you delete the entire Amoury Crate software the error is gone.
Anyone who uses AuraSync and has dynamic color profiles give it a try. For me it was definitely the cause. I discovered it through VR because I always had stuttering when playing VR and at some point I figured out Amoury Crate was the cause. I then always deleted parts of the software and the problem went away. Until I discovered yesterday through a lot of testing that the stuttering only occurs with dynamic color profiles. Then I remembered that I switched from a fixed to a dynamic profile just as FC25 started to stutter.
I hope it helps for you who also use ASUS RGB software. If you don't have Asus software you might still want to check your RGB software.