I tried switching from Firefox to Safari because I do heavy web research and Firefox takes way too much memory. After trying it for a week or so and trying to use some extensions to enhance Safari, I have failed to get essential functionality out of it and I simply give up : 1. It crashes: everything works OK for a while and then after you have over 100 tabs it just starts crashing or showing the spinning beach ball. Unacceptable, especially when you're using a 15" rMBP and the sites you were visiting were subscription-based and you can't recover the exact pages where you were because of having to log in again. 2. It loads pages slower than Firefox: What gives? I thought it was developed for Mac OS X? 3, Extensions don't work: Safari Adblock doesn't block YouTube, Facebook and Google ads, and the same goes for other sites. Adblock works fine on Firefox, though. 4. It doesn't have a built-in clear cache on exit function. All of this is very frustrating, and though I will miss the Reader and dictionary look up functions, those functions are not worth me stressing myself out every time I use it. Back to Firefox.