A controversial title, I know. I am running a 2009 MPB 2.26 C2D with 8GB RAM. I run regularly Lightroom and MS Outlook. In the past, I had Snow Leopard, Lightroom 3 and MS Office 2008. I was very pleased with performance. Recently, I upgraded to Mountain Lion, LR4 and MS Office 2011. My computer is slow now. It feels like a PC Actually, my work-issued Dell D630 feels snappier. It would be VERY difficult for me to reverse my software versions (ML, LR and Outlook), so I'm wondering if I should: a) rebuild my system from scratch. My ML install was an in-place upgrade, not a clean install. Would I benefit from rebuilding the system? I am not an expert at that, so it'll be a bit of a chore for me, or b) Would ML be happier on newer hardware? My CPU fans are running pretty high, too, much more than with SL. Would everything just be happier on a new machine with the new processors, etc. c) Should I (can I even???) swap out my DVD drive for a flash drive, and run my OS off there. Would that help at all? Just trying to look for solutions to move forward with, rather than backwards. To get my Apple joy back. Thanks for any help.