Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
I have a PB G4 1.5Ghz with 1.5Gb RAM and about 3-4 months ago started having lots of problems with lag/beachballs. I would consider myself a real basic user (Safari, Office, etc.), so I have no clue what is causing it.

It started happening right about the time I did an upgrade on Office (from the Microsoft AutoUpdater). If I restart, everything is fine for a few days and then I have to restart again.

Not trying to bash Microsoft, but it may be Office that is causing the problem...did you do the update as well?

No Office installed here and it is still really slow.
 
One thing I forgot to mention in my earlier post is, if you are short on memory, one thing you can do is to kill your dashboard widgets.

I don't know if it's a function of dashboard itself, or shoddy widget implementation, but even the really basic widgets like the calendar will use 5-8MB of PHYSICAL memory, regardless of whether or not the dashboard is currently displayed. So if you have say 5 dashboard widgets displayed, you can say 25-40MB of physical memory right there, which will in turn give your other applications more memory to work with, and reduce the beachballing.

If the problem is memory-related (which generally it seems to have been for me), you should almost never have to just restart your system in order to get it back up and running smoothly though. If you quit out of all your active applications, it will free up memory and it will be basically like restarting 95% of the time. Make sure you're actually quitting the apps with Cmd-Q, though, and not just closing the windows, cause that'll do nothing :p.
 
It's interesting, but I quit Quicksilver for a while and it is a lot more responsive now. I wouldn't say perfect but way better. Quicksilver didn't look like a memory or resource hog in activity monitor but it runs smoother now without it.
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.