CPU overload causing crackiling

Hi, still trying out the trial version before I buy. Is there a way to increase buffer size? I can’t seem to increase it to 512 as the slowest is 256. My pc laptop just cant handle that buffer size. It is a duo core i7. Does anyone else have a faster laptop that has had success with a buffer size below 256/

there must be another problem: buffer 256 should run smoothly on any modern cpu, your i7 cpu is fast enough. Please try and close all other apps.