Best macOS reccomendation for iMac(2019)

No one is lying to you.

The 2019 iMac can be configured with up to 64GB of RAM. If your mother’s iMac had been so configured then it probably would be performing much better with Sonoma or Sequoia.

RAM in the 27” iMac 2019 may be easily upgraded. The 21.5” iMac? Not so much. Check out the RAM offerings at macsales.com.

Another critical component that may be affecting performance is the startup drive. If the iMac is equipped with a 5400rpm rotational hard drive, then that will be a performance bottleneck. You might consider using an external SSD as

the startup driver instead.

It should be running on the most up-to-date version of Mac OS which as you know is Sequoia. The fact that the computer does not run well on Sequoia indicates there may be an issue with something that is installed on the computer. What that is, at this point is a mystery. Sequoia is stable and runs very well on my 2020 iMac as it does on millions of other similar machines.

I would recommend doing the following and we can look for obvious issues:

It will help us get a good idea of what is causing your problem if you provide a report of your system, that way we do not have to play 20 questions with you. The report we are requesting does NOT provide any personal information and is extremely safe to use. Please navigate towww.Etrecheck.com and download the free version of EtreCheck. Once you have you downloaded the app and installed it, please run the report and save it. This report will help us get a good idea what has been installed on your system and help us be able to diagnose what may be wrong.

When you have your report, you can attach it when you reply to this message and we can then review it and help you determine what is needed to get your system running well again. 

For instructions on how to download your EtreCheck report and attach it to your reply to this message please click How to use the Add Text Feature When Post… - Apple Community It is helpful to us if you download the report to your Desktop.

BTW, do she have any of the following third party apps installed on your Mac?

       •      Antivirus Apps

       •      Cleaning Apps

       •      Security Apps

       •      VPN Apps

       •      Maintenance Apps

If she does, you VERY likely discovered the root of the problem. These types of apps are completely worthless and do nothing to improve how Mac OS runs. They VERY often create just the type of problems your mom's Mac is experiencing! Because of this they should be uninstalled per the developers instructions.

The 21.5" 2019 iMac has two RAM slots, can officially take up to 32 GB of RAM, and can actually take up to 64 GB. However, the RAM sockets are sealed inside, and upgrading the RAM is a job for a repair shop.

The 27" 2019 iMac has four RAM slots, can officially take up to 64 GB of RAM, and can actually take up to 128 GB. Like all 27" iMacs (except for the 27" iMac Pro), this iMac has user-upgradable RAM.

Install memory in an iMac - Apple Support

Macs can be picky about RAM – so if you get more RAM for your iMac, I would suggest that you buy it from Other World Computing – whether it is you or a repair shop who installs it. OWC and Crucial used to be the two "go to" vendors for Mac RAM, but these days, Crucial seems to have gotten out of that business.

Other World Computing – OWC Memory Upgrades for iMac

Brendan_R86 wrote:

What is the best stable OS for this system?

One of the "most recent three": Ventura, Sonoma, or Sequoia. Some application vendors like Adobe and Microsoft have a policy of only supporting the "most recent three".

Note that the versions of Pages, Numbers, and Keynote in the App Store now require Sonoma or better – and some of Apple's latest keyboard and mice require Sequoia 15.1. Safari is distributed with macOS or via Software Update, but the release notes for Safari indicate that the latest version requires Ventura or better.

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