How to fix severe frame drops in complex scene transitions?

I'm fed up; this motherboard's VRM is like a sieve. Exploring ruins caused textures to flicker as GPU frequency dropped from 2100 to 1500MHz per GPU-Z. I tried limiting the GPU max frequency to 80% in the drivers, but that just tanked my FPS below 40. I used the GamePP BIOS Load-Line Voltage Guide to set a +0.05V Vcore offset per HWiNFO. GPU frequency stabilized at 2050MHz per GPU-Z, and CPU temperature stayed at 68-75℃ per AIDA64 with VRM at 75℃ per HWiNFO.