Low framerate in GZDoom specifically

[Berwick]

Hello and sorry if this is a common issue but I didn't see anything else like this posted.
Basically my frames DROP whenever something more intensive is happening like large numbers of monster and large areas, or when there are a few particle effects. For example in mods like High Noon Drifter and Trailblazer the frame rate drops from 120fps (which I think is still pretty low for a game like this) to 40 or sometimes even 20fps when the shooting starts getting hectic. This seems to be a GZDoom problem as one of the mods that I had this problem with (preacher) when ran in ZDoom had no frame drops at all.
My specs are
Intel Core i7
Nvidia GTX 1060
Windows 10 64bit

[Graf Zahl]

This sounds like you have some options enabled that increase processing time quite significantly. The most likely one is the Multisample setting in the video mode options. This one can even bring down a high end NVidia card.

[Berwick]

Thanks for responding to my problem, multi sampling was off but there were other options that I turned off that greatly increased performance.
I am having another problem however. In Preacher on GZDoom there is a render glitch that I don't know the name of but is common in source games. This is specific to GZDoom as ZDoom runs the mod just fine. Is this just a compatibility problem or am I able to fix it?
Screenshots:
https://imgur.com/a/NfnovZg