Got the same machine but mine is running slow seemingly since my update to Snow Leopard. However, part of the problem may be related to two things:
1. A 7200RPM hard drive. This is a known issue. I know I sent mine back to Apple (within the 1-year warranty) and they replaced it because it was failing. Now I have a Toshiba brand hard drive. Another ''however'' is that there seems to be some consensus that the SATA firmware/driver is in conflict with the configuration in general and while I don't know the 10.5.8 solution, I have heard that the upcoming update (10.6.2 Snow Leopard) is supposed to address this issue. It also makes for occasional stop-and-start video.
2. Permissions and disk repair. This is the easier of the issues and with you still running Leopard it is even better. Get AppleJack (totally free at VersionTracker.com). Get it. Love it. Live it. Install it and run it to fix all the important maintenance and repair tasks at boot-up. I cannot stress just how much of a savior AppleJack has been over the years from Tiger to Leopard. It is totally free and if I were to make a list of the most useful and best utilities ever created for Mac, this would be it. I'm just hoping the developer(s) hurry up and make a Snow Leopard-compatible version....soon. Also, check your fonts for corruption. Use the Font Book utility in the Utilities folder.
Both of these scenarios can make for ''slowness'' on an expensive laptop that should really just plain work. MacBook Pro owners paid a premium for a ''pro'' level machine and it should perform to this level.
Oh, forgot to mention that there was apparently a graphics card overheating issue that is also well known and specific to our model. Apple has already said that it will, warranty or not, replace faulty graphics cards. I haven't had to replace mine (yet if ever), but others have not been so lucky. Check into that too just FYI. Apparently this syndrome can manifest itself anytime during the life of the machine.
Good luck.
