Minecraft Shaders Lagging

I helped my brother build a new PC with a 9070xt + R7 7700 and 32 gigs of RAM and Minecraft is killing it. Other games that are supposed to be more intensive are fine, it's literally just minecraft - specifically with ANY shaderpack. Normal minecraft runs fantastic, but when we use any shaderpack - FPS is in the dumps. I checked the allocated memory, 8 should be fine for this. It's definitely using the dedicated graphics, no VSync, DP is on the GPU. The FPS goes around the 16-33 range even when using the "(internal)" shaderpack which I don't think does anything to change anything. Use an intensive shaderpack also around that range. Need help! TYIA