cleaning up an iMac

There is an excellent diagnostic tool available, Etrecheck. It just looks at your system and provides a detailed review of what you're running, how it's running, etc. Here's an excerpt from one for the developer's posts here in the forums:

"EtreCheck is designed to print out basic information about your machine in order to help the people who are trying to help you figure out why it is running slowly. It will report your machine model, amount of RAM, hard disk type and size, and any 3rd party software that runs in the background. It actually does much more than that, but those are the key features. EtreCheck will also alert you to significant problems that you might not have realized, like a failing hard drive, lack of RAM, lack of Time Machine backup, or an adware infection. The most recent version of EtreCheck will even help you remove the adware. EtreCheck doesn't automatically delete anything, but it will delete adware if you ask it to. It will also show you more details about things that could potentially be adware or malware."

It transmit no personal information. It's probably the top tool many of us use here to help diagnose problems with user's machines in order to find a solution.

I agree, just let OS X look after itself. OS X will run its own maintenance scripts automatically, just let your computer run over night occasionally. This is one of the primary reasons why I switched to Macs and linux years ago. It's probably much better now but I found my main use for windows was maintaining it.

I agree with OT. Etrecheck is the only third party utility I'd recommend for finding orphaned files and junk you don't need. It does no cleaning automatically, just gives you a snapshot of your system.

Other than that you can just manually go through your files and if you need to make space, move the larger less often used files off onto external drive.

None are recommended. They are a waste and are known to "clean" files they shouldn't.

Do you have a current performance problem with your Mac? Or why are you asking?

I suggest you do as Old Toad has recommended and download and run EtreCheck. Afterward post the report here and we will analyze it for you.

If you post a copy here, we can check it out for you.

Please post the report so we can review it for anything that could be detrimental for efficient performance.