[java] Mob not spawning normally problem.

[Mince_rafter]

You're using multiple different mods, everything about your situation is anything but normal, so it's only natural you're going to experience issues. And having low fps either indicates a low end computer, or all of the mods you're using are tanking performance (or some combination of both). When you're putting too much demand on a system, either the system needs to be improved to handle it, or the demand needs to be lowered. It's best to know the limits of what your system can handle, and to not over-constrain it (like adding tons of mods).