MBP massive performance slowdown

Question

Hello,
So I picked myself up a new MacBook Pro, standard 15 inch dual 2.8ghz model, about three weeks ago. I updated it to 10.6.2. For the first two weeks, it was fantastic in every way. About a week ago, there started to be occasional little 'glitches' in its operation - interactive things (clicking on a menu, changing text fields, entering text) would cause the computer to stall with the spinning rainbow pinwheel for 3-6 seconds. Over time, these became (and have remained - multiple stalls while opening Safari, navigating here, and writing this message) much more frequent. Other things that cause stalls include scrolling up/down documents/pdfs/web pages, opening folders, closing windows, and so on. The computer is now generally much slower than the old MacBook I had before. It used to be a speed demon.
Things I have done to try to resolve it / figure out what's going on:
1. Using activity monitor to watch for stray/processor hungry processes. Nothing unusual showed up, my cpu use averaged around 3% and hit a high around 18% during a period of editing a document that saw many stalls. The system never had less than 80% of the cpu idle and generally had more than 95%, so I feel insufficient cpu power is not the cause (plus, this happens frequently when I have only one or two applications open, and they're applications like Safari or TextEdit that should not come close to stressing this CPU. It also happens when playing games, and the games play/perform very smoothly except for stalls every 20-30 seconds.)
2. Checked /repaired permissions with Onyx and the Disc Utility while booted from the install disc. Also checked file structure / volume status / SMART status several times, came up good each time.
3. Booting from install disc, erasing the disk, reinstalling/reupdating the system. I did not zero out the hard disk, this seemed unecessary.
4. Repairing permissions as above, again. For what it's worth, a bunch of FlashPlayer related permissions came up as incorrect and were repaired, but this had no impact on the problem.
5. Reinstalling/updating Flash Player, then repairing permissions again just in case.
6. Briefly contemplated deleting stuff to free up hard drive space, before remembering that 454.56 gigs out of my 500 gigabyte drive are free, so hard drive space is clearly not the issue.
None of the above steps had a positive or otherwise noticeable impact on the condition.
So, yeah, my computer is becoming very difficult/slow to use and I have no idea why. Any suggestions about what is wrong and what I can do to fix it would be very appreciated. Gracias.

Answer 1

Repairing permissions should NOT be done using the install disk (http://support.apple.com/kb/HT1452) although I dought that's your problem.
As far as zeroing out the drive prior to re-install....I make it a practice to zero out the drive although I dought that's you problem either.
If after reinstalling didn't correct the problems you could have a hardware problem....try running the hardware test (http://support.apple.com/kb/HT1509)
Most suspect would be the RAM, HD, or logic board.....?
Have you tried to resetting:
SMC (http://support.apple.com/kb/HT3964)
PRAM & NVRAM (http://support.apple.com/kb/HT1379)