Presumably before you just used EZkeys mono-timbrally. Playing in MMO, although not quite like having 5 copies, does require the VST to create 5 internal ‘copies’ for each MIDI channel, so MMO wise it will use significantly more CPU resource. NO free lunches here.
I suspect this is pushing your box over its limits. One way to investigate this is to load up Task Manager (right click on the bottom tool bar) and see what the graph looks like.
here’s a shot of 14 tracks playing with Omnisphere (2 copies) Aruria Piano v2 and Stylus RMX, with Omnisphere picking up the burden multi-timbrally.
This munches up 12% of CPU on my 32GB, 4.9Gz, 16 thread i9-9900 . I suspect that your box was struggling to play the 5 extra tracks on top of anything else you had running. It looks like there were 3 synths, but in fact it was the equivalent of about 12
Re the last post … I checked and it’s not clear if EZkeys is multi-timbral, but probably not. I was thrown by the fact that you were sending multi-channels to it because it supported them, but if not, the question is why you would use MMO if it supports one channel only.
If it is mono-timbral, then it’s not clear how it would deal with processing other channels. One assumes it would either ignore the other channels or merge them together. Either way, it’s presumably not how Tootrack intended it to be used.