I you choose some basic and simple patches ( two oscillaot, one filter and two envelopes), you will be able to play several notes in polyphonic ( don't forgett to set "nbr released" to 1 or 2 ) and the MMV will not charge your CPU more than twice a standard VSTi. But If you choose FM presets, or multi oscillators ones, you will have some CPU overload when using polyphonic mode.
Xavier