Dear all, I have experienced a massive lag / non-responsive ui after updated to Yosemite. I'm using a Late 2013, Macbook Pro Retina 15" , Intel i7 2Ghz, Iris Pro, 8 GB 1600 MHz DDR3. Here are the list of obvious lags: System preferences - When open, will need to wait at least 5-10seconds Safari, all website loads very slow .. and non responsive. Most of the time it shows a white screen, and wait for almost 10seconds to load Anything on the menu/title bar, the spinning wheel will appear Everything much slower than before I have tried 1. Reduce transparency 2. PRAM Reset 3. Reinstall Yosemite 4. Repair Disk But all fails and the problems still persist. Any great guru can help here? Thank you!