Intel Imac running slow and sluggish

Question

I'm getting an awful lot of spinning colored ball delayed responses when performing most routine tasks in all my applications on my 4-year-old Intel 20" Imac under the latest snow Leopard. S
aving files and opening others and executing commands that used to happen in the blink of an eye now all take several seconds to happen. The dreaded spinning ball is up for many seconds while I wait !!
Would appreciate some general strategy advice on how I might use directory rebuild or Activity Monitor tools to find the culprit or culprits plural
My 250 Gig HD is divided into two partitions - 70 Gig for my Windows 7 Boot Camp partition and the balance of 180 GIG for OSX. The Mac partition is about 80 per cent full. Is it likely my drive is getting overloaded, or is it likelier an init or some phantom process running in the background is slowing everything down ?
Would appreciate some sage advice on where to start looking and things to try to speed this Mac up !
Should I, for instance, start by getting out my third party directory rebuild boot DVD after running Mac tools like Disk Utility to check for obvious volume problems ??

Answer 1

There are some simple troubleshooting steps you can take.
Be sure you drive is not overly full. Rule of thumb would be over 85%.
Create a new User go to System Preferences >> Accounts >> "+" (make it an admin acct) and test the apps in this new account, if they work the problem is isolated to your User and not systemwide.
If the issue is limited to your user account try starting up Safe Mode (It will take more time to startup in Safe Mode because it runs a directory check.)
If your apps functions correctly that way, go to System Preferences >> Accounts >> Login Items, and remove them. Boot normally and test. If not go to/Users/yourname/Library/Contextual Menu Items and move whatever is there to the desktop. Then do the same with /Library/Contextual Menu Items. Lastly, try moving/Users/yourname/Library/Fonts to your desktop and restarting.
Log out/in or restart, if that sorts it start putting items back one at a time until you find the culprit.
If the issue is systemwide then,You may be able to repair this with The 10.6.4 Combo Update This is a fuller install, as opposed to an incremental "delta" update so it should overwrite any files that are damaged or missing. It does not matter if you have applied it before.
Remember to Verify Disk before update and repair permissions after update from /Applications/Utilities/Disk Utility.
-mj