I have played Big Dig, Blightfall, Attack of the B-team, Hexxit, and some non official ones like Omega Adventure Pack and they're all seriously laggy. I can't figure out why because my computer is quite generous with it's specs, and I have allocated 10 GB of RAM to play these packs. My packs will be running smooth at first, but while I play I'll get serious FPS drops from 200 to around 20-30, which freezes my screen for a bit. I have put all my settings to fast, minimal, disabled vsync, distance chunks set to 6-8 and no clouds, shadows or bobbing.
NVIDIA GeForce RTX 2080 Ti
Intel(R) Core(TM) i9-9900KF CPU @ 3.60GHz
32gb RAM, Speed: 3200 MHz
I would love some help on this, thanks!