My 27inch new imac with fusion drive has issues with the OS, all my apps run super quick but the OS is really slow in transitions (opening folders, switch desktops, expose etc.). It wasn't doing this for the first month of use but has all of a sudden started. I tried an archive and install of the OS and still the same problem, I tried a full install of the OS then restored my data from a time machine backup and still same problem. Nothing major is showing in activity monitor and it is even like that when no 3rd party software is open or under a brand new user. Anyone have any ideas?