I have been having an issue with my macbook pro running very slowly lately. Everything just feels slugglish, and sometimes menus and other programs take a while to respond. I have 4 GB of RAM, and I just feel like things are running too slow for a computer with a Core2Duo and 4 Gigs of RAM. I have snow leopard installed.
Also, the computer came with 2GB, but I upgraded to 4 myself. I did not buy the memory from Apple though, I bought it directly from crucial. Is it possible the memory has gone bad or something. I really don't know what to do.
I swapped out my new RAM for my old RAM and it still ran slow and pinwheeled a lot. Also, when I run windows in bootcamp, windows seems sluggish too. I'm not really sure what's going on.
What do your swaps look like?
Activity Monitor - System Memory Tab.
What is listed for "Page Outs" and "Swap Used"?
Check this after your Mac starts showing the issue again.
It very well could be the HDD directory or a physical bad sector. I saw this same behavior and repaired with Diskwarrior. This failed and replacing the HDD solved the issue.
Do you still have the slowness problem when running OSX from the DVD (not running AHT)?
Is this symptom occasional, or all the time?
Most of the classic problems causing slowness that can be user fixed have been covered, but it does not mean totally eliminated.
The hard drive can still be intermittently bad despite the SMART status. I would put the original RAM back, and boot from an external Firewire hard drive with my backup HD clone. If you don't have one, you should - you might need it sooner than you think. This test can confirm if your internal HD is causing this or not.
I suppose it's also possible that you've developed a software problem and reloading OSX might help. This is quite a lot of work without a backup clone or Time Machine backup. You may have to take it to a technician if you don't feel up to doing this.
No offense.
Using the DVD is a terrible way to see how the system is running as it seeks all the time and any action must first be read by at the most a 16x read speed. Usually an 8x. You'll see the beachball MORE often.
I've just started having a similar problem. It happens only after the MacBook has been running awhile; the fans start up (I'm seeing about 95 CPU temp), every application slows down. Memory shows very little free, but ~1.25 GB (out of 4) in the inactive category, presumably still available.
Looking at Activity Monitor, none of the apps appear to be hogging CPU time; closing them down one by one doesn't have any effect. Shutting down and restarting does.
I will try more of the fixes suggested here; posting now in case this problem turns out to be more widespread at the moment.