You should also take all the "usual" steps to speed up a poorly performing Mac. I keep this response on file, since the question is asked very frequently. Here is the usual "recipe":
First, check that your processor is running full speed. In Tiger at least, go to Preferences, Energy Saver, Options and look at the drop box down near the bottom called Processor Performance. If it is not set to "Highest", set it to that right away. This maximizes performance, but for notebooks, it may run down the battery faster. Note that not all Macs have this setting - my certainly my PowerMac G5 tower does, but not all Macs do. For Leopard, the preference panel is a bit different in this regard, but poke around and make sure that you are set up for optimum performance, not optimum battery life.
Next, for Intel Macs, fire up Activity Monitor and check for any processes running that are PPC not Intel (this is shown in one of the rightmost columns of the Processes display). If you are routinely running a background process of perhaps even a widget that is PPC, that process is running under Rosetta and that is consuming more CPU. You might wish to upgrade it to a Universal Binary, or replace it with something else.
Next, download OnyX and run the complete set of clean up and maintenance scripts and then evaluate again. Get OnyX at:
http://www.titanium.free.fr/pgs/english.html
Next, you may wish to check that you have enough free space on your hard drive. Highlight the Macintosh HD icon on your desktop, CTL-click it and select Get Info from the resulting menu. Make sure you have a reasonable amount of space left. If not, a little spring cleaning may be in order.
There are two excellent apps for showing where all of your hard disk space has gone, Disk Inventory X and WhatSize. Get them at:
Disk Inventory X:
http://www.derlien.com
WhatSize:
http://www.id-design.com/software/whatsize
Both do a great job at letting you zero in on your largest disk space consumers, so that you can hunt down any rogue files (and both are freeware, which is good).
Finally, it is possible you may have some processes running that are consuming a lot of idle CPU, thus slowing down your machine overall. I had a bad widget that did this once. Open Activity Monitor and look at your "resting" CPU occupancy when you are not doing anything in particular with the machine. It should be pretty much zero (maybe 1% to 2% at most). If it not, identify the process or processes that are taking the time. What are they? Do you recognize them? Are they needed?
If you find one that is not needed, kill it and see how your machine starts to behave. If this is the cure, you will need to identify the startup item that launches it and delete it.
So, in summary then, take the following steps in order:
1/ Start with ensuring that your processor speed setting is full (applies to many Macs but not all)
2/ For Intel Macs, check for PPC processes and potentially prune them out
3/ Do Onyx based full maintenance
4/ Check that you have sufficient available disk space
5/ Search for processes that are consuming an unexpected amount of CPU
A final thought. If you routinely leave your web browser running when you are not using it, and have it open at a "busy" page like Mac-Forums, you will find that the Flash-based animated ads on the page consume a ridiculous amount of CPU time. If you want to leave your web browser loaded and running all the time, try pointing it a peaceful page like Google's basic search page - no ads, no unusual CPU consumption. This may help as well.
