If you actually do have 50 mods, that definitely can add to your low fps symptoms. Like others have said:
There are fps improvement mods, Vulkan can help some users, and the baseline settings like screen resolution and other in game options being lowered.

You need to get a control test to see how much of it is your system and settings vs mods by playing without any mods. If the difference between control and modded isn't that great, your mods are fine for now.

If the difference ends up being 5fps+ consistantly(which is 25% of your low balled fps) I'd blame the mods and start looking for ones to cut as well as looking for options to increase baseline fps.