Mac 21.5 retina 4k. 3ghz 6 core intel i5. 16GB memory. 1TB HD.205GB free. Original OS Mojave. Current OS Sequoia 15.3.1. Purchased 11/4/2019.
The computer is extremely slow . It takes approximately 39 minutes from restart until any program will open. I have not added and new programs, hardware or software in the past year.
iMac 21.5″, macOS 15.3
My advice is to replace the computer. It has a failing HD and Mac OS has been modified. Your #1 priority is to backup the computer using Time Machine and then test the Time Machine backup!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
A 2019 iMac (a based model 21.5" model at that) is NOT worth investing time, money or resources into repairing. I would recommend looking at a 2024 M4based Mac mini with 16GB of RAM and a 1TB SSD. This will far surpass the iMac in performance!!!!!!!!!!!!!!!!
My advice is to replace the computer. It has a failing HD and Mac OS has been modified. Your #1 priority is to backup the computer using Time Machine and then test the Time Machine backup!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
A 2019 iMac (a based model 21.5" model at that) is NOT worth investing time, money or resources into repairing. I would recommend looking at a 2024 M4based Mac mini with 16GB of RAM and a 1TB SSD. This will far surpass the iMac in performance!!!!!!!!!!!!!!!!
You could but I would not spend the money on it, I'd put that towards a much more up-to-date machine. Here is a link that shows how How to setup an external SSD as your startup disk
I see. you also installed and run CleanMyMac which is considered malware by experienced users on these forums. Mac OS does NOT require, benefit or in ANY WAY need any of the following types of third party apps:
Installing any of these has the exact opposite effect users want, they make Mac OS slow, unstable, appear buggy and makes Mac OS less secure. In short they are at best 100% worthless and at worst damaging.
If hard drive failure is making it take 39 minutes until you can open a program, the hard drive failure is far advanced.
Even updating existing backups may pose a risk to them. You may want to make further backups to a spare disk – then to try to reassemble files from older backups, and from any final one, on a new machine.
If the internal HD damaged, would I be able to boot from an external HD? If so, how?
Your computer shipped with Apple's Fusion drive, normally not slow.
However, Fusion consists of a small SSD linked by software to a larger mechanical hard drive. If the two components lose their software connect you get a Split Fusion drive" and dreadful performance. Split can be a fault in one of the drives or, more commonly, due to an ill-advised attempt to reinstall the operating system.
You can try fixing the split:
How to fix a split Fusion Drive - Apple Support
or the external boot drive option if that fails.
39 minutes until I can open a program upon startup
