Same here. Playing with i7 5820k, 32GB RAM, 2080Ti at 3440x1440.
I have the Dirt Rally 2.0 GOTY Edition.
It's the only game that has stuttering while playing, very annoying and unplayable. Trying lowering graphics, crowd, etc. No luck. Tried also the DirtFix (.dll), no luck.
I'm not using VR. I'm not using any wheel. I'm playing with the Xbox One S wireless controller with USB official wireless adapter from Microsoft. I repeat, this is the only game that gives me frame drops very often and I believe it's due USB pooling (of course, a part of the USB wireless adapter, I've connected my headset, keyboard, mouse...)
Can somebody help me?