Safari used to be absolutely miserable for browsing and opening a page with a lot of pictures/videos. It would load slow and just not let you scroll for a while and when you could the page splits and is choppy. Just really, really awful on Mavericks. Slow in general. Using the Safari on Yosemite it is night and day how much faster it is. I could see myself using Safari as the daily option instead of Opera. Very impressed. I'm not sure why it's so much faster now but I am happy about it.