Hey, I know this is an old thread but would you mind explaining how to set game process affinity to P-cores? Keep in mind, I don't have Intel. My whole specs are:

CPU - AMD Ryzen 5 3600X 6-Core Processor - 6 Cores RAM - 16 GB
GPU - AMD Radeon RX 5700 XT - Primary/Discrete
VRAM - 8176 MB - GDDR6 1750 MHz
Graphics - AMD Radeon RX 5700 XT
Graphics Manufacturer - Powered by AMD
Usable Memory Size - 8176 MB
Core Clock - 1795 MHz
Memory Type - GDDR6
Memory Clock - 1750 MHz
Memory Bit Rate - 14.00 Gbps
Total Memory Bandwidth - 448 GByte/s

I have pretty much the exact same issue as you. Like the way you explained it is 1 to 1 my problem. Random stuttering that's totally unexplainable. Whenever I'm doing anything, even something extremely undemanding it will stutter for a split second without fail. My PC is beefy enough to run this game at max settings and 120fps so it's not a tech issue. Sometimes I can ignore stuttering in games when I can expect it like if an entirely new level geometry is loading, but here it's immersion breaking because of its randomness