How can I speed up my iMac?

I hope the following is helpful to you in dealing with a slow computer. Often times there is a specific cause and other times any of the following actions may be helpful. They are “maintenance” steps which are often ignored.

·      It is important to occasionally restart a Mac. Ideally, once a week or more often. This does some system cleaning.

·      Regularly clearing the history of your browsers can help as all the data is stored in RAM. Clearing frees up RAM for system use.

·      Some people seldom empty their trash. If you haven’t, then do so. Also empty your email trash.

·      Some programs use a lot of RAM. (Like many Adobe apps and the Chrome browser.) When using them, close any other apps not being used.

·      Doing a restart in the safe mode can clear a number of problems. This is done by holding down the Shift key at start up. This process can take up to ten minutes while the computer is doing its maintenance and cleans the cache. You may then restart normally.

·      It is also a good idea to run the Disk Utility app. If it reports some issues, then rerun it repeatedly as needed until the final report is ok.

·      On some computers the problem may simply be that there is not enough RAM installed for RAM hungry programs that are being used. The very minimum amount of RAM we would recommend for computers running the Catalina, Big Sur or Monterey OS is 16 GB. This information is found by going to the Apple logo in the upper left corner of the finder and clicking on About This Mac. Note; not all computers are able to have RAM user installed. Some upgrades must be done by a qualified Apple service specialist.

·      Last, and most important, you should remove any and all maintenance and antivirus programs. They will cause problems and will significantly slow your computer.

·      It is also very useful to download and install the free app EtreCheck. Be sure to enable full disk access and run it. Save the report. You can post the results here at the bottom under “Additional text”. It will tell us exactly what you have installed which might be problematic. Then we can offer some suggestions   s

I hope these suggestions are helpful and enable you to speed up your computer.

iMacs have been in production for over 20 years, we need more information about your specific Mac. Please do the following:

It will help us get a good idea of what is causing your problem if you provide a report of your system, that way we do not have to play 20 questions with you. The report we are requesting does NOT provide any personal information and is extremely safe to use. Please navigate to www.Etrecheck.com and download the free version of EtreCheck. Once you have you downloaded the app and installed it, please run the report and save it. This report will help us get a good idea what has been installed on your system and help us be able to diagnose what may be wrong.

When you have your report, you can attach it when you reply to this message and we can then review it and help you determine what is needed to get your system running well again. 

For instructions on how to download your EtreCheck report and attach it to your reply to this message please click How to use the Add Text Feature When Post… - Apple Community

Also PLEASE read Writing an effective Apple Support Communities Question