Hi,
I will link to our documentation which touches on memory management: FMOD API | White Papers - Memory Management.
FMOD is designed to handle large amounts of Emitters through our Virtual Voice system outlined here: FMOD API | White Papers - Virtual Voices.
Could I get a screenshot of this reverb in your mixer?
If there are any effects that are not modulating and/or changing in real-time, it could help to bake those effects into the sound files in an external DAW.
The events are currently rather complex but nothing too insane.
hope this helps!