Mac OS X Speed Up?

[Floris1994]

If have been reading peoples experiences on upgrading to leopard from tiger and some people said it actually sped up their g4 computer or slowed a dual g5 down... Why does this happen? It doesn't make much sense.

 

[Matek]

Well, since it wouldn't make much sense for some hardware to become faster with a new version of the OS and other hardware to become slower, I think the answer is quite simple.

Leopard is slightly more demanding on hardware than Leopard, which means some people with well-maintained machines may notice their systems are slower with the new OS.

On the other hand - some people don't clean up their systems regularly, so when they erased their Tiger installation and installed a fresh copy of Leopard, the system got faster simply because they got rid of all the crap that has gathered on their machine since the last install.