One of the most common technical support questions we get is that the customer’s Mac seems to be running very slow. Slow performance can be caused by any number of things but here are a few places to look.
1) My Hard Drive is Full
Many times this it the culprit. Your drive stores your files but is also used as “virtual memory” by your Mac and also stores invisible and temporary files. Our recommendation is to always leave at least 10% of your hard drive’s capacity available. Your Mac will slow down as the operating system searches for open sectors of that drive and puts data in small increments on the available sections. Leaving 10% free will address this issue.
2) Permission Conflicts
Your files in OS X have a set of permissions, which determine which users or applications have access to them. Sometimes, for one reason or another, these permissions are wrong and that can slow your system down. To repair permissions you use Disk Utility which is located in the Utilities folder in your Applications folder. Select your drive and push the “Repair Permissions” button.
3) Bad Preferences
If you find that it is one particular application that slows your Mac down when you launch it, it very well be that application has a corrupt preference file. Preference files are re-created if you delete them and are located in the Library. What I do is to find the preference file of the slow application and move it to the desktop and then relaunch the application to force it to make a new preference file. Once things seem to be running at full speed again you can trash the preference file that you moved to your desktop.
4) Have You Left Your App Running?
If you neglect to quit out of applications that you only use occasionally and leave a bunch of them running in the background, this can obviously slow your Mac way down. Each application uses memory and CPU resources and some may actually “leak” memory which means that they longer they run, the more memory they use.
This also could be the case if you have too many startup items or a very crowded widget page, which are just small applications that take up resources.
5) Not Enough RAM
If your Mac is one of the diminishing number where you can add more RAM, this could be a solution, too. You can see if you are RAM-starved by checking the Activity Monitor and clicking on the Memory tab.