AMD Ryzen 5 3400G (CPU) with an MSI x470 (MoBo), 16GB RAM, a Radeon 5600XT (GPU), and SSD.
I have an issue where my games have "FPS stuttering". This is where the FPS drops to 35-50 FPS from 150 FPS several times each second. The result is choppy gameplay based on inconsistent frames.
I noticed that Core0 is at max utilization while the other 7 hover around 24-30%. Disabling Core0 for the particular game solves the problem. The FPS is consistent and hovers around 300 FPS. Core0 drops to about 67% utilization while the other 7 cores increase to 30-40%. I have to use this fix everytime I launch any game.
Why is this happening, and is there an optimization that does this?
Could be some installed software. You should try monitoring CPU performance across running programs when this happens, to see if something is periodically hammering the CPU. Especially something low-level, like anti-virus, as some things in Windows only work on core 0.