Having had to use safari on tiger recently Ive noticed there is a big difference between the OSX versions, Tigers version of 3.1.2 is slow in rendering pages compaired to leopards version of 3.1.2 it gets even worse the lower the upload speed, Leopard continues to connect to sites tiger just fails unless you shut down and restart it on tiger, why?, this is on the same G4 power book.
And also there are a few sites were neither version would render the site properly (reported the site ) and on one the forum on a site it failed to run but use the nightly build from web kit and the forum would work fine. What ever Apple has disabled in there builds that webkit does not is a pain.
If only Fire fox did not over ride other apps and use 100% cpu when running flash videos I would switch plus it needs a better RSS feed reader plugins.