My late 2015 iMac running Monterey 12.7.6 is extremely slow to load applications and especially at startup

Question

My late 2015 iMac running Monterey 12.7.6 is extremely slow to load applications and especially at startup

Late 2015 iMac. Running on Monterey 12.7.6. It has been upgraded to SDS hard disc, and I use time-machine on an external SDS hard disc. But it is currently extremely, maddeningly, slow, especially at start-up. There doesn't seem to be any particular load on CPU, memory, or disc usage. But it's SO painfully slow. Every application I want to start doesn't start - after some time it starts to bounce up and down on the dock, then goes to "Application not responding". Eventually, if I wait long enough, it'll work. But it wasn't this slow a couple of months ago (it was pretty responsive) and I don't understand why it is now, I haven't installed any new applications and I'm not doing anything different. But I can end up taking 30 minutes just to start up and print a document!

[Re-Titled by Moderator]

Original Title: iMac extremely slow to load applications, especially on first starting up. Monterey 12.7.6

iMac 21.5″, macOS 12.7

Posted on Jun 11, 2025 07:19 AM

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Answer 1

MartinR

Level 7

23,517 points

Jun 11, 2025 08:11 AM in response to spitfirethecat

More details needed ...

If these are actually "SDS" drives pls. identify the exact setup ... makes, models, software, etc. It would be highly unusual to be using SDS on an iMac. Or did you actually mean "SSD" as in Solid State Drive?

How much RAM is in your iMac?

What is the capacity of your system drive & how much free space is on it (GB and/or %-age)?

If you can manage it, pls. install & run Etrecheck and post the report here. It's a free diagnostic utility that will provide details that will be helpful figuring out what's going on with your iMac. It's safe to use and does not reveal any personal information.

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Answer 2

Jun 16, 2025 03:37 AM in response to MartinR

Thanks for reply. And oh dear... it should indeed say SSD not SDS. Unsure of make of internal drive, external is Seagate. Internal storage is 1TB, 467GB available. RAM only 8GB, but it's been able to cope fine until very recently. External time-machine drive also 1TB, only 195GB available. I will have a go at installing and running Etrecheck.

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Answer 3

Jun 16, 2025 10:35 PM in response to spitfirethecat

spitfirethecat wrote:

Internal storage is 1TB

Your tag line says that your Late 2015 iMac is a 21.5" one. That implies that it has either a slow 1 TB 2.5" 5400 rpm mechanical hard drive, or a slow 1 TB Fusion Drive which pairs one of those with 24 GB of SSD space.

The original 1 TB Fusion Drives had 128 GB of SSD storage. In Late 2015, Apple got stingy, reducing the amount from 128 GB to 24 GB. It is prime real estate, but there is simply too little of it.

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My late 2015 iMac running Monterey 12.7.6 is extremely slow to load applications and especially at startup

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