IMac 21.5", half 2017 working slow even after formatting

I don't see any signs that the drive is failing or even worn out, but some drive failures don't always show up in the health report.

Try running the iMac without the SD card just in case this is affecting your system. Disconnect all external devices to see how the system performs just in case one of the devices has a problem.

I would also suggest uninstalling the Western Digital external drive software by following the manufacturer's instructions. This software is not needed to manage an external drive and it can cause system issues. If you absolutely insist on the WD software, then make sure it is updated to the latest version. It would still be a good test to uninstall it to see if it helps with system performance.

Run the Apple Diagnostics.

If this doesn't help, then having an Apple Authorized Service Provider upgrade the iMac to an SSD would be a great way to increase system performance as suggested by @rkaufmann87.

From what I can see there is nothing wrong with the computer other than it's a base 21.5" iMac that only has 8GB of RAM and a glacially slow 5400 RPM HD. If you use it for anything more than surfing the web and getting e-mail then it's likely overloaded. Speeding it up would entail getting an external SSD and using that as your startup drive after migrating your internal HD's contents to the SSD.

The report mentions a failing hard drive and the symptoms you describe are consistent with that possibility.

You can run DriveDX if you want more confirmation and post the report here using the "Additional Text" icon which looks like a piece of paper.

I suspect the EtreCheck hard drive warning is coming from this:

Performance:

System Load: 1.51 (1 min ago) 1.36 (5 min ago) 1.33 (15 min ago)

Nominal I/O speed: 0.36 MB/s

File system: 26.01 seconds

Write speed: 30 MB/s

Read speed: 75 MB/s

A write speed of 30MB/s is slow, even for a 3GBps 5400 RPM drive. Should be 50-70.

Try removing all the Western Digital software that EtreCheck identifies with "wdc". That stuff has never run well and I've had stalls and overheating when running it on both current Intel-powered Mac and older PowerPC Macs. Several posters here said that WD tech told them not to use their WD Mac software. There have been different methods of removing it so you may need to contact WD support for the "how to." However, DO NOT download one of the generic "uninstaller" apps all the search engine push through their advertising. Too many are are simply carriers to give you malware.

However, removing that would be an incremental improvement for an iMac with 8GB RAM and a slow mechanical hard drive that is trying to run Adobe CC and Premiere, very high-demand programs.

Given the HD may be failing and you need more speed, the best option with this computer is to get an external solid state drive (SSD), clone your internal drive to it, and set it as your boot volume. A USB 3 external enclosure with a 6GBps SSD inside will move those read/write speeds to about 400MB/s–almost 9X what you now get– and will make a huge difference is how the computer performs.

A Thunderbolt 3 external SSD boot drive would be even faster but they quite pricy.

If you decide to replace the iMac with a one more capablle on handing the Adobe pro apps, do whatever you can to afford the Apple SSD option. These are the EtreCheck scores for the 1TB SSD in my 2017 iMac 27" 5K:

Performance:

    System Load: 1.66 (1 min ago) 1.42 (5 min ago) 1.31 (15 min ago)

    Nominal I/O speed: 0.23 MB/s

    File system: 20.35 seconds

    Write speed:  2156 MB/s

    Read speed:  2863 MB/s

I'm 90% sure that the problem doesn't come from WD software, infact I had these problems before installing it.

Agreed. I wrote that removing the WD stuff....

...would be an incremental improvement for an iMac with 8GB RAM and a slow mechanical hard drive that is trying to run Adobe CC and Premiere, very high-demand programs.

It was an incidental finding, but I have seen a few EtreCheck reports where removing extraneous software improved the hard drive scores. Now the we know the problem predated that software, we can scratch it off the list.

From what I read the only solution is using an external SSD?

Well, you can have an Apple Authorized Service Provider open the sealed case, replace internal drive with an SSD, and add RAM while the computer is open. expect 2-3 hours labor at US$70-80 per hour plus the cost of the upgrade parts and the reseal kit. If your iMac is under Apple Care, that is not an option unless you are willing to kiss off the paid coverage.

The remaining options are the external SSD or selling that iMac and getting one more suitable to Adobe pro apps.

Hello, Albertodileonardo.

Sorry to hear you're having this problem with your iMac. You've done well to post your EtreCheck report. It notes several things that are likely causing your slowdown.

First, in Major Issues it note a failing hard drive. That is huge. My first advise is to backup your data as soon as possible, before you spend any more time doing anything else with your computer. Then have that drive replaced. Replace it with an SSD if you can afford it. If not an SSD, then replace it with a 7200 rpm hdd. The 5400 rpm drive that Apple used in that machine really isn't fast enough on a good day to allow Catalina to run well.

Otherwise, the report looks pretty clean to me. It appears the failing drive is the issue.

I trust the etrecheck report more than the Drive DX report...

Failing hard drive - This machine has a hard drive that appears to be failing.

wow. can't believe i missed seeing the entire convo.  🤦‍♂️

going for coffee now.