I've just upgraded to GPO 4 and am having problems with the VST version in Sonar 8. The audio stutters whenever the mod wheel is moved or aftertouch is sent and the CPU spikes alarmingly. When playing just notes the CPU hovers around 2% but rises to 50% or more when the mod wheel is 1st moved. This does settle down but the audio stutters continuously.
The problem soes not occur when the equivalent patch is loaded into Kontakt 3.5 nor with the stan alone player.
System Pentium Dual Core E5200 2.00 GB RAM, Audio card Terratec DMX 6fire 24/96, Sonar 126.96.36.1992, Windows XP SP3