Briefly, every time that "address book sync" becomes active on the Mac side, the computer on both the Mac and the Windows side becomes incredibly slow, almost usable. If I disable the "address book sync" through the activity monitor (force quit), the computer on both the Mac and Windows side restores to normal speed. I have 4 CPU's on this MAc book pro and i have configured parallels to 2 for the Mac side and 2 for the Windows side. I have also allocated 2GB of memory to the Windows 7 side which is within the recommended range of 512MB to 4GB (Maximum memory is 16BG). I have also noticed in "activity monitor" that the process name "prl_vm_app" can run as high as 200% of cpu usage and vary anywhere from its current level whilst writing this email of 5% upwards. This does not however seem to affect the speed of the computer and again this is being caused by "address book sync". For information I am running Outlook on the windows side and using "contacts" and this is also being replicated on the mac side in "contacts". Whenever I update or enter a new contact in the windows side (Contacts in outlook) then address book sync starts shortly after on the Mac side and the computer slows considerably. I have iCloud working on the mac side and windows side syncing my contacts calendar etc. Does anyone have any suggestions?