Hi Fran.

A single patch can run 21 plug-ins at the same time.

That said, remember this is only a tiny little 333 euro device with a 1GHz processor. Just because it can run 21 plugins at the same time doesn't mean it will. Same goes for your Mediastation.

Btw: It is running Linux too. It's got a separate CPU for the OS and the 1GHz processor is devoted entirely to the VSTi's your running so at no point does it get sluggish.