You can try running through our PC Optimization Guide by typing keyword PC Optimization in the knowledge base. One setting which is particularly important is the step to enable DMA on the hard drives.

You can also go to Options - Audio - Advanced and change the disk IO Buffer Size from the default of 64kb to 128, 256, or even 512kb. This will cause it to pause at the start of playback just a bit, but will lower the disk requirements while playing back, and can help you get a higher track count.