I've been reading all the threads the past few days and finally updated to Lion. I have a MacPro 5.1 with 24GB of RAM and a SSD for boot/apps. Instantly I noticed how much faster everything was running. My mac booted in half the time, literally. Everything in finder, safari, mail, etc is so much zippier. I know many others have had the opposite effect. After upgrading, things have slowed down, either slightly or considerably. I guess the differences could be contributed to different hardware, but I would think that as long as the hardware being used fits the requirements of Lion there would not be issues. What's the deal?