Thats really strange.
Pls, load jamstix in an empty project and hit “create song” (wizzard) straight away and then play the song. My vsti-performance stays between 10%-20%, realtime peaks around 40%. And that, while jamstix is playing 105voices max. Seems to be ok.
(i7 950 here)
jamstix3.zip (1.26 KB)