cannot load efi/drivers/testsupport.efi - iMac 21.5" late 2012

Hey spatsy,

We understand you're not getting the performance you'd expect on your iMac and we'll do all we can to help out.

Sounds like you attempted to run Apple Diagnostics on this iMac, but it failed to run. As suggested under the 'Learn more' section in the following article Use Apple Diagnostics to test your Mac,

"On an Intel-based Mac, if you can't start Apple Diagnostics with the D key, try these solutions:

• Press and hold Option-D at startup to use Apple Diagnostics over the internet.
• Make sure that your Mac isn't using a firmware password."

If the report comes back with no issues found, we would suggest focusing on this article If your Mac runs slowly, which can help resolve performance issues on Mac. When you open this link, be sure to choose your macOS version under the 'Select Version' drop-down menu at the top of the article.

We hope this information helps out.

Take care!

Unfortunately with some system firmware revisions the online Apple Diagnostics are broken. Perhaps upgrading macOS will provide an updated firmware that works with the online diagnostics.

The two most common problems for a slow iMac is a software issue or more likely a failing hard drive. Run EtreCheck and DriveDx and post the reports here using the "Additional Text" icon which looks like a piece of paper.

Your hard drive is worn out as the hard drive has an extremely high "Load Cycle Count" (attribute# 193) that is at almost 2M (most drive manufacturers have a lifetime limit about 800K). Whenever the "Load Cycle Count" gets near or exceeds the manufacturer's lifetime expectations I find hard drives tend to slow down and have other odd behaviors.

Since the hard drive is just worn out and does actually have any bad blocks you could easily clone the system to an external USB3 drive and boot from an external drive to continue using your iMac without needing to open the iMac. After cloning the drive and confirming the external drive is working properly you can erase the internal drive so macOS doesn't get confused since I have seen macOS inadvertently access items on the other drive which can be dangerous (It is best to unmount or eject the internal drive to confirm the external drive is working fine on its own and not accessing anything from the internal drive before erasing the internal drive). Another option is to perform a clean install of macOS on an external drive and migrate just the user account(s) and manually reinstall the third party apps.

Always have frequent and regular backups.

Assuming your Mac has the standard configuration, it means that you have a super slow 5400 rpm spinning drive which does everything at a snail's speed. There is nothing one can do about that except get an external SSD, clone your system to it and use that as your main boot drive. That is, unless your hard drive is failing - in which case an authorized service provider may replace the old spinning drive with an SSD.

Here are install videos for a late 2012 21.5" iMac:

https://eshop.macsales.com/installvideos/imac_21inch_late_2012/

Running an etrecheck report first would be helpful.

Looking at your etrecheck, a couple of things:

First you have this useless stuff installed:

Clean My Mac.

Get the uninstall instructions from their website and delete it. It is worthless and will slow down your computer.

And, you still have Flash Player installed - go to the Adobe website and uninstall it. It has been discontinued.

You also have Gatekeeper disabled. Not a good idea - consider changing that back to the setting it should be.

And, I was right about your slow hard drive and the minimal RAM.

I will leave the analysis of the DriveDx report in the very capable hands of HWTech as I'm not that familiar with it.

spatsy,

Thanks for the update. If you're unable to complete a diagnostics to isolate the issue further, it would be best to get in contact with Apple Support from here. They can be reached using this link: Get Support

Thanks.

Sorry, I missed that - personally, I would not put too much money into anything electronic that is 9 years old. That is ancient in technology. Aside from your hard drive, the logic board and/or graphics card can fail also. So, I'd put that into a jar to start saving for a newer one. Apple usually has some good deals on refurbished units - same warranty as new ones and you can buy Applecare. That is where I get all my stuff:

https://www.apple.com/shop/refurbished

Take it to an independent AASP, they may be able to help you out. If you don't know of any in your area please use the following link to find one.

AASP Locator

If you want to clone a boot drive I recommend using Carbon Copy Cloner (CCC) as it is easy to use and also restores the hidden recovery partition.

Another option is to perform a clean install and migrate from a backup. Using CCC is sometimes the better option if you have third party software with license keys (MS Office) since Migration Assistant/Setup Assistant doesn't always automatically transfer those licenses.

As for those _crx files I don't know. I don't use any browser extensions/add-ons and I have never looked into those folders before.