Hi !
I have read elsewere (on 2 other forums) that to have a speedier OS X, one should install a fresh version of OS 9 on one partition and OS X on another partition. These readers had experienced first with the "OS X over OS 9" type of install with abysmal speed results, and re-installing on two partition "quickly" corrected the speed issues.
As for myself, I cannot say, having not received my MacOS X CD Yet.
Hope this helps.