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2019 iMac Very Slow

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webbymac

macrumors member
Original poster
Aug 23, 2009
55
4
Hi, a colleague of mine has a 2019 iMac that is so slow to boot up and login and use; it's becoming unusable.

Specs:
2019 iMac 4K 21.5in
3.6Ghz quad core i3
32GB RAM
Fusion drive
Ventura 13.7.2

I have run first aid in disk utility and it's ok.

Read and write speeds seem ok at around 830 write and 1200 Read.

I've offloaded the photo library to an external disk so there is plenty of storage space, around 260gb free.

As you can see, it has plenty of RAM.

She generally uses it for Mail, Word, Teams, Powerpoint, and sometimes switches between work and personal accounts.

I've checked for malware, I've checked for memory hoggers, high CPU users and there's nothing.

Why is it so slow? What have I missed? I know it's only an i3 but it should be capable of this surely, no?

Any help much appreciated, before they bin it and buy a new one (trying to avoid that).

Thanks

p.s. I have considered using an external SSD and running/booting from that, but I think maybe the R/W speeds of the internal are ok, for what it is. Would the external help do you think?
 
My gut tells me it's the Fusion Drive. I don't know why but those drives appear to slow down with age. My wife had a similar machine and it got so slow it was useless. I did a nuke and pave more than once and that didn't help. You can try the external. I finally just replaced my wife's iMac with an M3 iMac and runs on those tasks like a bat out of hell.
 
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1200 read speeds
and
830 write speeds...

... are actually MORE THAN you would get from an external USB3.1 gen2 SSD.
External USB3.1 gen2 SSDs offer reads in the 910MBps range.

This indicates that the fusion drive is still doing ok.
I'm wondering if the problems are software-related.

What I'd suggest or try if you put this into my hands:

Backup the iMac using a CLONED BACKUP such as SuperDuper or CarbonCopyCloner (both are free to download and use for 30 days).

Then, disconnect the backup.

Boot to INTERNET recovery (command-OPTION-R at boot).

When you get to the internet utilities, use disk utility to erase the fusion drive.
Make sure you go to the "view" menu and choose "show all devices".
Otherwise you won't see the fusion drive (it should be "the top line" in the "list on the left").

Then quit disk utility and open the OS installer, and install a completely fresh copy of Ventura.

When done, the iMac should boot to the "initial setup screen" (choose your language).

CONNECT YOUR BACKUP at this time.

Now, do the setup process all over again, migrating from the backup when setup assistant asks for it.

See if this works.

If it doesn't, there are other pathways to walk...
 
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Fishrrman said:
1200 read speeds
and
830 write speeds...

... are actually MORE THAN you would get from an external USB3.1 gen2 SSD.
External USB3.1 gen2 SSDs offer reads in the 910MBps range.

This indicates that the fusion drive is still doing ok.
I'm wondering if the problems are software-related.

What I'd suggest or try if you put this into my hands:

Backup the iMac using a CLONED BACKUP such as SuperDuper or CarbonCopyCloner (both are free to download and use for 30 days).

Then, disconnect the backup.

Boot to INTERNET recovery (command-OPTION-R at boot).

When you get to the internet utilities, use disk utility to erase the fusion drive.
Make sure you go to the "view" menu and choose "show all devices".
Otherwise you won't see the fusion drive (it should be "the top line" in the "list on the left").

Then quit disk utility and open the OS installer, and install a completely fresh copy of Ventura.

When done, the iMac should boot to the "initial setup screen" (choose your language).

CONNECT YOUR BACKUP at this time.

Now, do the setup process all over again, migrating from the backup when setup assistant asks for it.

See if this works.

If it doesn't, there are other pathways to walk...
Click to expand...
Thanks.

So when you say software related, do you mean OS? Cos the rest of it, I'll just be putting back when I restore/migrate won't I?

Note: I did recently update the OS from Big Sur to Ventura, but I did not erase the Drive beforehand, just in the hope that a newer OS would help things.
 
With Apple, newer OS on old hardware usually leads to the mysterious "long in tooth" effect. Coincidence or something legit? One option drives people to replace by spending money on a new model and the other leads to no new money. You can jump to your own con$piracy conclusion... or not.

You might want to downgrade the OS and get back to the speed you had.

While the Fusion Drive may seem fine now, they are prone to problems by about this many years. If you want to keep using this Mac for many more years, you might want to replace Fusion with a new SSD drive... basically replacing it before it conks. The problem with Fusion is generally too many writes to its tiny SSD portion. An SSD can only take so many writes. You may be near that limit now and it might be playing a role in what you are experiencing.
 
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webbymac said:
Read and write speeds seem ok at around 830 write and 1200 Read.
Click to expand...
How many IOPS (input/output operations per second)? I think this is where HDDs are mostly lacking compared to SSDs, and these days programmers think they can use the storage without considering how expensive that operation is.
 
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webbymac said:
I have run first aid on the boot drive. Is AD more thorough?

Or I could run Etrecheck....?
Click to expand...
Apple Diagnostics is more thorough in that it tests the hardware and sensors, not just disks. I honestly don't know whether running Apple Diagnostics does the same thing as Disk Utility First Aid in the context of disks. I would hope it is more thorough than just a file system check. AD is different than Etrecheck. First Aid is different than Etrecheck. These tools target different things. Run them all ;-)
 
speeds are not indicative of the actual speed of the fusion drive because anytime you read and write to a fusion drive, You are writing to the ssd until you fill the cache. Peel open the iMac and either replace the SSD portion of the fusion drive with a larger one and remove the hard disk or replace the hard disk with a SATA SSD.
 
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You need to boot from a modern SSD, not from that old fusion drive. It may or may not be causing this problem, but it will cause problems. Even with plenty of RAM keep the boot drive less than 50%-80% full.

I had a friend with similar slow boot on an old box and I found a reported OS bug and fixed it. I will report back if I can remember the specifics...

Edit: I remember I reviewed Activity Monitor and one app was using inappropriate huge RAM. That led to Apple's info on the bug and how to work around it.
 
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webbymac said:
Hi, a colleague of mine has a 2019 iMac that is so slow to boot up and login and use; it's becoming unusable.

Specs:
2019 iMac 4K 21.5in
3.6Ghz quad core i3
32GB RAM
Fusion drive
Ventura 13.7.2

I have run first aid in disk utility and it's ok.

Read and write speeds seem ok at around 830 write and 1200 Read.

I've offloaded the photo library to an external disk so there is plenty of storage space, around 260gb free.

As you can see, it has plenty of RAM.

She generally uses it for Mail, Word, Teams, Powerpoint, and sometimes switches between work and personal accounts.

I've checked for malware, I've checked for memory hoggers, high CPU users and there's nothing.

Why is it so slow? What have I missed? I know it's only an i3 but it should be capable of this surely, no?

Any help much appreciated, before they bin it and buy a new one (trying to avoid that).

Thanks

p.s. I have considered using an external SSD and running/booting from that, but I think maybe the R/W speeds of the internal are ok, for what it is. Would the external help do you think?
Click to expand...

As others have mentioned, it is probably the Fusion drive. You might try benchmarking with ‎AmorphousDiskMark. Consider testing with Test Size greater than RAM (e.g. 64GB). That will also benchmark random I/O and that is where modern software tends to get bogged down.

But to your question, that hardware is more than capable of running those applications. Ideally Apple would have included a T2 on that model but that shouldn't be noticeable unless doing H.264/H.265 encoding. There might also be some overhead if you have FileVault turned on.

FYI, I tested my Mac Mini 2018 w/i3 @ 3.6Ghz and 8GB of RAM that was smooth as silk under Mojave and it performed nearly identically on a clean install of Monterey. I have not yet tested head-to-head but don't believe Ventura is noticablely slower than Monterey all else being equal, and yours should run even better with the Radeon graphics and 32GB of RAM. Mine does have an internal SSD to run the OS.


P.S.When it is feeling sluggish, I am guessing you already looked at Activity Monitor and CPU ~ 0% while not actively using the mouse/keyboard and there's no swapping/plenty of free RAM even with all those applications open?
 
Folks...

The OP posted the speeds he's getting from the fusion drive.
They looked quite good to me.

An external USB3.1 gen2 drive would be SLOWER.

Slow boot -- BEFORE the user logs in -- suggests something is wrong with system software.

Hmmm... calling the OP:
After the user logs in, are things STILL slow?
Going from the login screen to the finder?

Tell us... how do things run once the user is logged into her account and running apps?
 
Yes, but fusion is basically ticking time bomb. Generally drives don't fade... so measuring speed doesn't give us a clue that a drive is dying. More typically, it's fine today and dead tomorrow. If it's fine, it will do well in speed tests, etc. If it's dead, crisis + panic + a lot of "now what?" and "how do I recover?" follows.

I've seen enough of these threads to suspect Fusion is at risk... if not the cause... it will likely be the cause of a different problem soon. Replace it or get something booting externally to cut it out of a test equation. The latter would likely be a cheap & easy way to test a gut guess that it actually IS fusion... in spite of drive speed tests in posts #1.
 
My 2019 iMac takes up to 20min to fully load on startup, after that the speed is fine.

Have already replaced the HD once, now DriveDX shows it's nearing EOL again (based on average expectancy).
 
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WebHead said:
My 2019 iMac takes up to 20min to fully load on startup, after that the speed is fine.

Have already replaced the HD once, now DriveDX shows it's nearing EOL again (based on average expectancy).
Click to expand...

I would find that concerning -- my Mac Mini 2018 w/i3 & 8GB boots Monterey in ~ 18 seconds (time to login screen with maybe 1-2 seconds from login to desktop). The settle time (when all of macOS's various background checks/indexing/etc finish) takes a bit longer but the system is reasonably usable in the meantime. If yours is a rotating HD and DriveDx is saying its nearing EOL based on SMART readings, I'd replace. Soon.

Ideally with a pure SSD solution. Recent macOS as well as more and more other software is better optimized for SSD versus HDD.
 
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bzgnyc2 said:
I would find that concerning -- my Mac Mini 2018 w/i3 & 8GB boots Monterey in ~ 18 seconds (time to login screen with maybe 1-2 seconds from login to desktop). The settle time (when all of macOS's various background checks/indexing/etc finish) takes a bit longer but the system is reasonably usable in the meantime. If yours is a rotating HD and DriveDx is saying its nearing EOL based on SMART readings, I'd replace. Soon.

Ideally with a pure SSD solution. Recent macOS as well as more and more other software is better optimized for SSD versus HDD.
Click to expand...

Thank you, yes, I have replacement SSDs all set to go, have just been procrastinating. But the system is fully backed up with Time Machine.

When I say it takes 20min, that's my "settle time" - you can still perform tasks in the interim. But it takes 20min for, eg, desktop widgets to appear and for hanging to stop.
 
It's 100% the Fusion Drive. No one should have a spinning disk in 2025.

I have a 2017 iMac with SSD, and it's still really really fast. I use it 8h every day at work.
 
webbymac said:
Read and write speeds seem ok at around 830 write and 1200 Read.
Click to expand...
That's just large sequential read and write. Most read and writes on boot drives are small random blocks. In addition, those fusion drives are notorious for causing issues. So that doesn't necessarily rule out your fusion drive as contributing to the problem.

It's a very low-end iMac (i3), so it may not be worth additional investment. But it does have a beautiful screen, and for < $100 you can but a good internal 1 TB SSD. [I think the fusion drive stays, but you add the SSD and use that as your main boot drive.] You'd just need to get an adapter (≈$15?). I had a 2 TB SSD installed in my 2019 iMac (in my case it didn't have a fusion drive, so this was a replacement for the stock 512 GB SSD).

Doing the replacement requires removing the screen, which I didn't want to do. So I dropped off my replacement SSD, adapter, and iMac with the local campus bookstore, which is also an authorized Apple service center, and they charged me $100 for labor. So that would cost you ≈$200 total. [I also got a heat sink, which may or may not be necessary.]

For more info., see this megathread:
forums.macrumors.com

A list of successful iMac 27" (2012-2019) SSD upgrades

Here you can find and discuss all the collected knowledge regarding upgrading the HDD, blade SSD and CPU of a 27" iMac 2012-2019, as well as a list of performed upgrades. Here is a list of all 27" iMac models subjected in this thread: Late 2012 - 13.2 - MD095LL/A (2.9Ghz i5-3470S, HDD only /...
forums.macrumors.com forums.macrumors.com

My other suggestion would be to do a clean install: Put everything on a robust backup (e.g., using Carbon Copy Cloner), then wipe the drive, reinstall the OS, and then reinstall each app from scratch. [You'll want to screenshot all your configurations before doing this, to make it easier to restore their configurations.] That way you get rid of any cruft (e.g., kernel extensions) that may have accumulated over the years. Be prepared to spend a whole weekend doing this. It's time-consuming, but can be sort of fun if you have the right mindset, since it re-introduces you to each of your apps.
 
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As others have noted there seems to be something unusually wrong here, but I would add that that particular i3 was an awful chip performance wise because it doesn’t have any form of turbo boost that Intel chips really rely on to get good responsiveness.

I still run a 2015 MBP with the 2.8 Ghz i7, and that particular i3 in the iMac benchmarks worse even than that decade old machine.
 
webbymac said:
Read and write speeds seem ok at around 830 write and 1200 Read.
Click to expand...
Can you please be more specific? Where did you get these values and what unit are they in? (KB/sec, MB/sec) Maybe a screenshot would help.

I would try to complete wipe the Mac, do a clean install (without restoring from any backup), then check if things get better.
If yes, it's the old system (crud that has been accrued over time). - In that case you should NOT try to restore from backup, but only copy manually the absolutely needed files from the backup.
If no, it's the hardware (slow processor, slow drive). time to buy something new or go back to an older OS (which is not recommended due to lack of updates.)
 
TheSl0th said:
As others have noted there seems to be something unusually wrong here, but I would add that that particular i3 was an awful chip performance wise because it doesn’t have any form of turbo boost that Intel chips really rely on to get good responsiveness.
Click to expand...

I have a Mac Mini 2018 with that chip and the i3 is not the problem. If OP's system is sluggish on general/productivity apps, a 20% clock burst isn't going to make a difference. It is more than capable of keeping up especially when backed with 32GB of RAM and paired with the AMD graphics in OP's system.

TheSl0th said:
I still run a 2015 MBP with the 2.8 Ghz i7, and that particular i3 in the iMac benchmarks worse even than that decade old machine.
Click to expand...

If your 2015 MBP is good enough to still run today then OP's iMac should also be good enough. While your i7 has about a 13% advantage on multi-core performance, it is no better at single core. On the other hand, the Radeon graphics in OP's iMac is likely faster than the one in your MBP (assuming it has the dGPU option).

Yours was a pretty good system for the time while the processors in the 2019 iMac followed Intel's long plateau. It should have been faster but it wasn't. Thus creating the opening for Apple Silicon. Then while both are a fraction of an M4 iMac, both are still fast enough to run general/productivity software today (excepting HDD/fusion drives and misaligned OS/software).
 
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webbymac said:
Hi, a colleague of mine has a 2019 iMac that is so slow to boot up and login and use; it's becoming unusable.

Specs:
2019 iMac 4K 21.5in
3.6Ghz quad core i3
32GB RAM
Fusion drive
Ventura 13.7.2
[...]
Why is it so slow? What have I missed? I know it's only an i3 but it should be capable of this surely, no?
Click to expand...

As someone who's had one fail, I'd bet money it's the Fusion Drive. The SSD part is generally insanely tiny and gets worn out from read/write cycles. The way the Fusion Drive works is by migrating whatever you're actively working on from the HDD to the SSD. Tons of data moving back and forth constantly, on a little 32 GB drive or whatever, and eventually the thing just maxes out on cycles and doesn't work well anymore.

People point fingers at the HDD on a Fusion Drive, but the fact is the files you're actively working on are actually on the SSD, and if you're seeing erratic behavior I'd look at the wear levels there first.

This is what happened to my 2014 iMac 5K -- it started slowing down and getting weird, and I used DriveDx to check the health of the SSD and found it was down below 10% of its lifespan left. Any Fusion Drives still in active use at this point should be looked at with suspicion.

Also, since this is an Intel Mac, you could always just get your hands on a reasonably fast USB external, create a boot drive and see how it runs off that. Seems to me that alone might tell you all you need to know about the state of your internal drive.
 
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ignatius observed:
"This is what happened to my 2014 iMac 5K -- it started slowing down and getting weird, and I used DriveDx to check the health of the SSD and found it was down below 10% of its lifespan left. Any Fusion Drives still in active use at this point should be looked at with suspicion."

So much for all those folks who brush off excessive VM disk swapping (on m-series Macs) with claims that "you'll never wear out that SSD" ...
 
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