Are you using Wifi on your music pc? Also did you install Win 8 over the top of vista? Both of these gave me problems.
A clean C drive install of win 8 and latest wifi driver made a big difference.
Also if your project has several audio automation envelopes you may well need to increase your audio file buffer to help prevent crackles and pops.
Finally have you got the Win 8 updates installed? There were issues with loading audio drivers in Win 8 until mid Jan