I am running an iMac Intel Core Duo, 3.06GZ and 4GB Memory with Mac OS 10.7 Lion. I installed a trial version of NTSF for Mac. As soon as the driver was installed and the Preference Pane opened and my NTSF formatted external drive was mounted, my whole system slowed down immensely. My menu meters registered constant activity from 50-80%, even with nothing running. Everything took forever to open and respond. After taking forever to uninstall NTSF, my computer is back to normal. I would like to use NTSF as I have a WD 1TB NTSF formatted volume which needs to be shared with another Windows user, but I can't take a chance on buying it until this problem is solved. Any help would be appreciated.