I've upgraded to the new OSX versions as they have come out over the years but simply put my performance on Yosemite was sluggish and frustrating. Frequent lockups and slow write speeds on Blackmagic (read was always good around 260). I went through several troubleshooting sessions, tweaks etc. and in the end went back to a CMD+R last week. Now I am back on Lion and everything seems to be just fine performance wise compared to my Yosemite experience. I am running a 2010 White unibody Macbook 7,1 with a Samsung 250gb 840 EVO SSD with updated firmware and 8gb of RAM. So my question to fellow 2010 White Macbook unibody owners, what OSX version are you running and how's the overall performance?