All computers, both Mac and PC, tend to slow in performance the more you use them. As more files accumulate on a Mac Mini, OS X tends to "bog down" slightly. However, there are some relatively easy tasks that you can perform within OS X to get your Mac Mini running faster.
Speeding Up a Mac Mini
Repair disk permissions. Navigate to the Mac OS X Disk Utility by using the path "Finder > Applications > Utilities > Disk Utility." Select your Mac Mini's main hard drive in the left-hand side window. Click the "Repair Disk Permissions" button located in the lower portion of the main pane within the first aid tab. Repairing disk permissions takes approximately 15 minutes, depending on how much information you have on your Mac Mini. If you do not already, you should regularly repair disk permissions on your Mac Mini every time new software is installed or a Mac OS X update is made.
Perform regular Mac OS X updates. Click the Apple logo in the upper left-hand side of your Mac Mini's desktop. Select "Software Update" from the drop-down menu. Software Update takes a couple of minutes to connect with Apple and check for new updates. Click the "Install" button to install any available updates. It is recommended to regularly install software updates, as they fix many bugs with OS X and add security updates.
Consider doing hardware upgrades. Check your Mac Mini's RAM by clicking the Apple logo in the upper left of the desktop. Select the first option, "About This Mac," from the drop-down menu. Look at the second listing in the "About This Mac" pop-up box. It will say something like "2GB 667 MHz DDR2 SDRAM." If this number is less than 2GB on your Mac Mini, consider upgrading to 2GB of RAM memory or higher.
Clear unused applications from your Dashboard. Click the "Dashboard" icon in your Mac Mini's dock. Click the small transparent "+" sign located in the lower left side of the dock. Click the exit sign next to any widgets that are not commonly used. Many Dashboard widgets continue to stay running in the background once you use the Dashboard.
Do a Safari reset. After a while, the Safari Web browser can begin to accumulate a significant amount of temporary, unneeded files. These files eventually begin to bog down your system. Open Safari. Click the "Safari" heading located right next to the Apple sign in the left-hand corner of your desktop. Select "Reset Safari" from the drop-down menu. Check any files that you don't need stored on your Mac Mini and hit the "Reset" button.