7-zip is the fastest compression tool I have come across. Ironically, it does a better job with Zip rather than the native 7z format.

Also it is one of the two native 64bit compression tools available (AFAIK); the other one being Squeez. But Squeez is nowhere near 7-zip's speed. I wish they made it more user friendly and easy to use as WinRAR. 64bit helps to improve 7-zip's performance up to 80%. Even in 32bit mode, it is still faster than WinRAR's compress/decompress performance.
One problem is that 7-zip has trouble extracting split RAR files that I download most of the times via torrents, using the
context menu entry (it doesn't show up

). So I have to keep WinRAR for those.
