Hi there! I' have a mid 2011 iMac with a 2.7GHz quad core i7 and a 5,400 rpm 1TB HDD. Now it takes more than a minute to boot and finish loading the desktop. I've been thinking about putting in an SSD but it seems to be quite a surgery to install it without permanently removing the original HDD and DVD superdrive. So I want to see if Yosemite has a faster boot time/ general improvement in performance. I may just do a clean install of Yosemite if so, before getting it into the operating theatre. Cheers!