Slow iMac (Retina 5K, 27-inch, 2019)macOS Sequoia 15.3

rather than playing 20 questions, i'm thinking you should download and run the free version of EtreCheck so we can see if you have some software installed that is causing your issue. make sure you give "full disk access" to etrecheck. Learn how to use it by reading Using EtreCheck. if you need help interpreting the report, you can see how to post the report here by reading How to use the Add Text Feature When Posting Large Amounts of Text, i.e. an Etrecheck Report. and it automatically obscures sensitive things (like serial numbers) so you don't have to worry about sharing the report here.

no, you don't want or need ANY antivirus apps on a Mac. unlike windows, Macs are not susceptible to viruses. apple already provides all the protection that you need to not get a virus.

the only "protection" that you need is safe computing practices. to learn about that, you should read Effective defenses against malware and other threats - Apple Community. it's a long article, but it's worth your time to read every word.

Anthony1741 wrote:

Thanks, I will investigate that. In order to improve the boot time, what sort of SSD would work, there seem to be a lot of variants?

I personally use two Samsung T7 SSDs for that purpose. one macOS on each. they offer a good compromise between price and performance. but there are MANY different SSDs that range from fast to blazingly fast. it's just a matter of "how fast do you want your wallet to go?" I recommend going to OWC’s website and see what they have to offer.

Is it possible to prevent Bitdefender from loading and operating, also intego?

you should completely uninstall them. just turning them off usually won't help.

Anthony1741 wrote:

Thanks, so am I correct in that you recommend:

1- Uninstalling both Intego and Bitdefender

yes, they are garbage.

2- Install an external SSD to handle the MACOS

you don't install an external SSD. you just connect it to an USB port. preferably to one of the TB ports.

So is the External SSD only for the MACOS? or other user data as well?

yes, you could run macOS and store extra data but that depends on the size of the new SSD, as well as much data you already have on the Mac. I personally keep very little on my local drive.

Thanks for all your help!!

you're welcome. :)

the first thing I saw was that you have a Fusion Drive with a very tiny 28GB SSD portion. those don't always play nice with any macOS from Big Sur and later. it might seem drastic, but IMHO, the easiest way to speed things up is with loading macOS onto an external SSD, and using that as your boot drive. to implement that, please see Use an external SSD as your startup disk with your iMac or Mac mini - User Tip.

and then, I noticed that you have bitdefender, as well as intego installed. those apps and similar apps are neither needed nor recommended on a Mac. they consume system resources while providing ZERO protection or benefit. you would do well to uninstall them using the developers' instructions.

Anthony1741 wrote:

only problem is that I cannot find a way to rename the Macintosh HD on the internal Fusion drive.

you should be able to do that within disk utility.

Maybe it's not necessary.

no, it is not absolutely necessary to rename it. it would still function the same way regardless.

Anyway very happy now and a big thanks to you.

you're welcome. I'm glad you've got it sorted. :)

@anthony Great that you resolved it Could you please share what you did to fix - as many suggestions were given. Thanks