To expand on rampant memory use by safari and web process. After my other comment, I instaled click to flash and an ad blocker to see if it really was Apple or Adobe. Well, Apple can't blame Adobe or Flash, as it still gobbles up GBs of memory. Slower than it used to possibly, but when you keep running into trouble with Safari slowing to a crawl, even with a core i7 + 16GB RAM and the fastest SSD you can buy???
I never run into memory trouble with firefox, but they keep killing extensions with their rapid development scheme and versioning. Small tool developers can't keep up.
Another issue since Mountain Lion is that Safari will vanish frequently with a right-click open link in new tab. I've been getting it pretty consistently with opening google results in new tabs. Researched ot. People have been reporting this since mountain lion came out! With a consistent pattern in console? So why not fix this??? Knock on wood, a reset has cured it for now.