FS9 and sound card question? Tweaker?

Since I installed fs 9 , yes I have the stutturs, jitters, some time the simruns awesome, most times it don't. I have tried many tweaks,some have shown improvement..but my sound whil running the sim, fluctuates, andpanning gives me scratchy sounds, also going into the menu, and the mouse pointer is a little slow at times. this happens at any resolution. I have the latest drivers.O BTW, it is a santa cruz sound card ?Mb Any help appr. WOW when the sim works, decneding through the clouds is as real as it gets. Those with no probs must be thrilled .