Crack sound´s with ANA

I bought the ANA synth and when i use it with Cubase 5, even if it´s just one synth and i make a beat, and add some other instruments from other vst the ANA vst seem´s to make my sound crack down until it start´s to slow down everything until i remove it, i put the buffer size up but that doesn´t seem to work any tips on how to fix this ? i got the system requirements for the synth so don´t know what the problem could be cause this dosn´t happen with massive kontakt sylenth1 or nexus. :pinch:

What are your system specs?

Windows 7 home premiumbr
processor: AMD ATHLON™ II X2 220 2.80 GHzbr
Ram 4,00 GBbr

do you have a soundcard?br
If you are using onboard sound this can really slow the CPU
Your CPU is rated at 2251 on
My mac laptop is about 8000 and Desktop 13500 for