iMac too slow

GGfromTS wrote:

Please read "attach the SSD" instead of "install the SSD" in my earlier message, sorry !

Thanks! "Install" made me flinch!

The reason I refer buying the enclosure and the SSD separately is that too many "name brand" external drives tend to under-inform the buyer about speed ratings. Also, the pre-formatting that comes with those is too often Windows-centric or they use a proprietary partitioning scheme that will just make life harder. As I said, to get max speed from the external SSD option, the enclosure must be USB3 or higher, and the SSD must be rates at SATA 6GB/sec.

As I will be doing this conversion for my daughter's 2017 4K iMac once we feel safe traveling again, I have already picked out the parts I plan to use:

Enclosure: https://eshop.macsales.com/item/OWC/MEPMTCES/

Enclosure power supply (optional but highly recommend for a drive used as the boot volume):

https://eshop.macsales.com/item/OWC/MOTGPWR/

Solid-state Drive: 500GB OWC Mercury Electra 6G SATA 2.5-inch SSD

There the option for a 1TB size if you wish to march the capacity of your internal drive.

How to put that SSD in the enclosure: https://eshop.macsales.com/installvideos/enc_owc_elite_al_mini_hd/

Hi,

Try to update from 10.15.6 to 10.15.7.

Then start up in Safe Mode then normal boot could solve the slowness of your iMac.

https://support.apple.com/guide/mac-help/start-up-your-mac-in-safe-mode-mh21245/mac

I don't see any software "red flags."

If you are seeing slow booting and slow app launching, I believe you are suffering what so many other users of 2012-2019 21.5-inch iMacs have: a slow 2.5-inch mechanical hard drive:

Drives:

disk0 - APPLE HDD HTS541010A9E632 1.00 TB (Mechanical - 5400 RPM)

Internal SATA 3 Gigabit Serial ATA

that produced these drive scores:

Performance:

System Load: 1.10 (1 min ago) 0.85 (5 min ago) 0.92 (15 min ago)

Nominal I/O speed: 1.18 MB/s

File system: 32.91 seconds

Write speed: 91 MB/s

Read speed: 92 MB/s

I collect drive scores and yours is performing about as high as can be expected for that drive type. Actually surprised me.

By comparison, these are the same scores from our geriatric 2011 21.5-inch iMac with 8GB RAM.

Performance:

    System Load: 1.62 (1 min ago) 1.67 (5 min ago) 1.87 (15 min ago)

    Nominal I/O speed: 0.05 MB/s

    File system: 38.28 seconds

    Write speed:  112 MB/s

    Read speed:  91 MB/s

That is not much progress.

Prior to 2012, the entry-level drives in iMac 21.5-inch models were slowed (like yours) by being rated at 3GB/sec (1/2 the speed of the computer's logic board drive bus) but were 7200rpm, and were the more robust 3.5-inch form factor instead of the delicate 2.5-inch laptop drive yours has.

Due to the difficulties and hazards in opening the iMacs sealed-case design, the most cost-effective improvement is a solid-state drive (SSD) in an external USB enclosure. The enclosure MUST be rated USB3 to work at all, and the SSD in the enclosure must be rated SATA 6GB for best speed.

That combo will bump those transfer speeds to about 400MB/sec and that will make a very apparent difference in the "peppiness" of the computer.

The cost effectiveness is for about US$100 you can get a 500GB drive and the enclosure. I buy them separately to make sure I have the right specs. It does not have to be as large as your current drive because your current drive will still be available for storing large files like photos, music and movies. You clone the internal drive to the external SSD and use System Prefs to set the SSD as the boot partition.

When you are done with this computer, you still have an external drive that can work on "whatever's next." What is is questionable is the cost effectiveness of have a professional open the computer and upgrade to an internal SSD. Labor cost in my area (Inland NW United States) would be about $160 on top of the cost of the drive and ancillary installation parts.

If you are interested in this option I can give you links to the parts I would buy to do this for one of my family's Macs..