Robert: if you can see some of the best fights of Foreman and Norton in their prime, you can get a good sense of their relative speed and power. I think if Foreman was slower (hand speed) it wasn't by too much.
Tyson in his prime was blazingly fast (feet and hands both)...there is no doubt....his jabs and combinations were vicious and his attacks were brutal, but many times with inferior opponents. I pitied anyone that got in the ring with him when Tyson was aged 19 - 28.
Ali fought at a time when the overall quality of the fighters was better and he still beat them -- sometimes handily. As I wrote earlier...comparisons of fighters of different eras is a dubious endeavor. I'm pretty sure ESPN has some of the classic fights of the 60s-80s it runs regularly. Check out Ali-Foreman fight. Of course, Ali-Frazier should be watched too..but Frazier wasn't AS blazingly fast (as Tyson)..he was just was incredibly strong, skilled..and you could hit him with anything...or drop a safe on him ...and he still kept on coming. Reminded me of a shark!
But here's another thing that Ali had that none of the others had of any era. He had creativity and as a fight tacticiand he was unsurapssed. He could change his tactics to suit the opponent. It's amazing when you see how he adapted..even as his own abilitiies eroded later in his career.