I also have very annoying stutters when taxiing with the FBW A320 and a Flight Plan loaded into FMC 
. Locked @30 FpS with Nvidia CP, but stuttering is there every 1-2 seconds, especially in turns.
Asus x570
Ryzen 5800x
32GB 3600 Gskill Neo
Asus RTX 3080 TUF OC