Usually that would imply you are CPU limited, and is different to a stutter issue.
Can i see HWinfo64 screenshots that show your CPU clockspeed and temps, with min max and average visible? First link of my sig has info on it, if needed.
By clicking the arrows in the bottom left, and closing a few irrelevant sensors i can get CPU clocks, temps, and power on the left with GPU readings on the right, all in the one screenshot.
My screenshot here is idle on a system doing nothing, we'd be looking for something like your max CPU Clocks being low, temps being high, that sort of thing.
View attachment 221550