Increase the H/W Buffer Size and CPU Limit percentage in the Hardware Setup dialog (refer to the Pro Tools Reference Guide fordetails) to get better system performance. With slower CPUs, you may also need to reduce the number of RTAS plug-ins used in the session to get acceptable results. In addition to slower screen redraws and UI responsiveness, larger Hardware Buffer sizes can affect automation accuracy for plug-in parameters and mute data, as well as timing for MIDI tracks.