Hi guys, This isn't a complaint or a whinge ... 2007 iMac. Yosemite is working terrifically on this old iMac. I absolutely love it !! One curious and I have to admit, annoying, anomaly is that Mission Control gives quite a stutter when opened, and when I go to change space, when there is more than one Space occupied. This was as smooth as silk with Mavericks .... I have turned off desktop in MC preferences (whatever it means) as someone on the web suggested, but it makes no difference. I realise it may be just a product of my old iMac but because it is performing so well in other respects I wondered if there is any issue with anyone else or any ideas on what else might be causing it ? Any ideas ?