Running First Aid for slow Mac

It may just mean that you need to run Disk Utility > First Aid while the iMac is started up in macOS Recovery.

You can also run Safe Mode, as per > Use safe mode to isolate issues with your Mac - Apple Support and then restart your iMac normally and test it.

In addition to doing those two things, you can also download and run the free version of EtreCheck Pro and post back here with the Report as per the instructions.

to get EtreCheck Pro from the App Store, go to > https://apps.apple.com/us/app/etrecheck/id1423715984?mt=12

to get EtreCheck Pro directly from the Developer, go to > https://etrecheck.com/

First of all you are not running First Aid on your Mac's drive, but the Recovery Mode boot volume. You need to select the correct volume for you Mac's boot drive. Unless you have renamed it, the default name for a macOS boot volume is "Macintosh HD".

Actually the report looks really good for a base model 21.5" that has a really slow 5400rpm HDD and only 8GB of RAM. Also very good, no third party AVware, Junkware or Cleaning App's that will bog things down and cause problems. The drive speed is normaly and the RAM is not upgradable, so there's not a lot more that you can do, except to try and quit process that are no longer needed and try to stream-line your usage.

Plain and simple, if you want or need a faster Mac, that can do more than that one?

Then your option include:

1. Installing macOS on an external USB 3.0 SSD or an external Thunderbolt SSD and running from it.
2. Get a faster 21.5" with an SSD and more RAM or get a 27" with an SSD and upgradable RAM slots.

peatmac wrote:

What puzzles me is why it’s suddenly gone so slow. It’s worked well for years, never the fastest but certainly not so slow doing anything that I could find fault and more than adequate for what I was using it for. Suddenly it takes forever to open any app, finder, safari or indeed carry out any function at all - basically unusable now!

Hmm... try this, go to Applications > Utilities > open Activity Monitor > select the CPU tab and look to see if you have a Process that is using a large amount of CPU. In addition to quitting high CPU processes, you can also use Activity Monitor to look for and quit processes that consuming a lot of RAM.

see > How to use Activity Monitor on your Mac - Apple Support

Is it easy to install macOS on an external USB to maybe help things along...?

That depends, how well do you know macOS Recovery and Disk Utility?

First off, you will need to buy or build an external SSD. It must be an SSD in a USB 3.0 or Thunderbolt enclosure. Using anything less, will be slower than your current setup.

Then you will need to Format, Install macOS and Migrate to the SSD. To do that, study some of the following links, to see if this is something that you want to do.

https://discussions.apple.com/thread/8234833

https://www.youtube.com/watch?v=xw00mPVCG2Q

https://www.applevis.com/blog/speed-old-mac-cheap-installing-operating-system-external-ssd

for more, see > install macos on external ssd

Ah... yes, good catch there HWTech.