Hi,
I have the same problem and found this solution under cubase :
1- load mmv_efx as a VST insert effect in any audio channel in the mixer
2- edit mmv EFW : it is very slow
3- then load mmv as a VST instrument
4- edit MMV vsti : it should be OK
I tried the same think with psycle; it works too.
I tried with 2 instances of MMV vsti; it does not work
If you load VSTI first, it is very Slow and the efx is fast !!!
Hope it helps.