I am starting to feel like I am pack in the dreaded world of Windows. Since "upgrading" to Yosemite, not only has Aperture started taking about a minute and a half to load - it used to load quite fast, but I am suffering at least three complete system freezes daily. The mouse pointer will stay active, but everything is dead. Nothing can be activated requiring a complete, long, re-boot. I am about to cash it in on Yosemite an revert back to a system that allowed everything to function normally and quickly. Interestingly, my Memdiag program always shows plenty of usable memory when the system freezes so it is not a function of that being jammed. Any suggestions appreciated. There is a possibility that Aperture might potentially be a culprit in that as an avid, very active photographer, it is often running in the background during the day.