If that is the case, chances are that you have clogged up your Desktop with dozens of files. Placing all your "must have” files on the Desktop isn’t the best way to use your Mac, but if you insist on doing it that way, you’ll see some improvement in speed by collecting those files into categories and creating folders for each category. The fewer files and folders you have in the Desktop, the faster your Mac will run.
Sometimes simply restarting the Mac will improve speed performance.
Try this: log out of your normal account and log in with a different account. If that other account seems to be running fine, then you need to perform some system maintenance on your account.
More memory does not necessarily speed up a computer unless you have the minimum or less than what the OS version requires. Even then, more memory is really only for the gamer or video editor. I always recommend the maximum memory for any computer just to be totally certain that low memory is not going to be a problem. If you’re running several applications at the same time (when it is loaded into memory, there’s a dot under the icon in the Dock) and you are low on memory, the system has to temporarily swap them out to the hard drive to make room for the one application that you are actually using. This swapping back and forth slows things down considerably, and more memory can improve on that.
Replacing a hard drive with an SSD will speed things up, but it doesn’t necessarily solve the problem of why your computer is slow.
If you have installed additional fonts on your computer, that will definitely slow down starting up the computer and starting up applications that use fonts, especially word processors. Use Font Book to remove fonts that you really know you’re not about to use, but be aware that you cannot remove any system fonts.
Declutter your disk by emptying your Trash often, including the Trash in Mail - they are not the same Trash.
Perform routine system maintenance. Junk accumulates on any computer. You might have deleted an application by just dragging it to the Trash - and that does not delete all the files associated with the application. Cache files and log files build up over time. Really old email messages and messages with attachments simply use up space, although they can slow down a search somewhat if you have thousands of old emails hanging around. A free utility called ONYX can do the job, but takes some manual intervention. There’s a different version for each version of mac OS X starting with 10.2. CleanMyMac 3 does all the same things with a single click and has some additional utilities that are well worth the price.
Do you shut off your Mac every night? That might not give Spotlight the time it needs to build a snapshot of the files on your Mac. If Spotlight doesn’t have a current build, it takes longer to find things on the Mac. It might take a couple of days for Spotlight to build a complete snapshot on a large file system, so be sure to give Spotlight plenty of time to do its job - and often!
Malware on a Mac can slow things down because some Malware constantly runs in the background snooping on what you are doing and reporting back to its owner. Malwarebytes (not free) or Sophos Home or Avast can ensure that malware doesn’t stay on your computer. Do NOT use more than one anti-virus application on your computer (such as Sophos Home and Avast). Malwarebytes isn’t an anti-virus app, so it can run alongside an anti-virus app. However, do NOT let Malwarebytes run in the background as this will slow down your computer. Only run Malwarebytes manually when you feel like letting it check out your computer’s status.
For additional tips, see MacAttorney’s “Macintosh OS X Slowdown Solutions.”
John R. Carter Sr.