On some sites, it's perfect. On others, it's painfully terrible. My system: http://note.io/YReHrc My Safari extensions: http://note.io/XTVFd1 Here, for example, performance is absolutely terrible. And here, it couldn't possibly be any smoother. I just tried disabling all extensions, one by one, and page-loading times seem significantly reduced (another matter I'll have to investigate as well now!). Scrolling performance, however, does not seem affected. On Google Chrome, I do not appear to have this issue. Or perhaps I do, but I never notice, while on Safari it regularly bothers me. Am I the only one or do you have this problem as well?