Stuttering or choppy playback
If playback is stuttering, you might be using too much CPU. If you use Windows' TaskManager to check for CPU, keep in mind that Buzz usually only uses 1 CPU (even with multi-cpu enabled), so that on a dual core system, max CPU load will be 50% and 25% on a quad core system.
Stuff you might try: Disabling reverbs, lowering the samplerate, quitting other applications that use CPU. Switching to waveout instead of ASIO might also give you a few percent extra. Don't use FFT based plugins like Jupiter in ASIO mode.
If you hear a slight ringning noise on top of sounds that are supposed to be clean
Try changing the samplerate to 48000 instead of 44100, as some on-board soundcards only support this rate properly (like e.g. the one in some HP computers.)