It's especially slow after a restart or login. Even when it's been on overnight, the first use of Safari is incredibly slow. I have 538 GB free on the internal boot drive. The same hardware runs well when it's running Windows. I'm running Sequoia Version 15.7.2, and this iMac cannot be upgraded to Tahoe.
iMac 27″, macOS 15.7
Very slow to go from login to the desktop appearing.
That observation, combined with Safari and Microsoft Word being slow to launch and Word's poor performance after it launches are symptoms consistent with a startup drive (Fusion Drive in that Mac) that is not performing well. Noticeably lagging keyboard input is another troublesome sign it is operating in a state of failure.
Safe Mode takes a long time to boot but once the login screen appears and you log in, everything should work just as well as it would after rebooting normally. That does not seem to be happening in your case.
Conclusively diagnosing a failed startup drive is not a straightforward task. Apple Diagnostics is almost certain to find nothing wrong, and Disk Utility probably won't either. You could even take the Mac to Apple and they would reach the same conclusion: everything is just fine.
You might try "repairing" the startup disk: How to repair a Mac storage device with Disk Utility - Apple Support. That must be accomplished in Recovery mode as the passage indicates:
"If you’re repairing your Mac startup disk or your Mac doesn’t start up all the way, start up from macOS Recovery."
The reason for quoting "repair" is that it tends to be a temporary fix, at best. Go ahead and try it anyway.
Using a utility such as DriveDX might reveal more justification for concluding the startup disk (Fusion Drive) isn't working properly, but I have little personal confidence in it. If all symptoms point in the direction of a failed startup disk, and they are, in all likelihood it needs to be replaced. Besides, drives can't be fixed, not in any permanent sense.
If you are so inclined, download DriveDX and post its report. Perhaps it will reveal something more conclusive.
Very slow to go from login to the desktop appearing.
That observation, combined with Safari and Microsoft Word being slow to launch and Word's poor performance after it launches are symptoms consistent with a startup drive (Fusion Drive in that Mac) that is not performing well. Noticeably lagging keyboard input is another troublesome sign it is operating in a state of failure.
Safe Mode takes a long time to boot but once the login screen appears and you log in, everything should work just as well as it would after rebooting normally. That does not seem to be happening in your case.
Conclusively diagnosing a failed startup drive is not a straightforward task. Apple Diagnostics is almost certain to find nothing wrong, and Disk Utility probably won't either. You could even take the Mac to Apple and they would reach the same conclusion: everything is just fine.
You might try "repairing" the startup disk: How to repair a Mac storage device with Disk Utility - Apple Support. That must be accomplished in Recovery mode as the passage indicates:
"If you’re repairing your Mac startup disk or your Mac doesn’t start up all the way, start up from macOS Recovery."
The reason for quoting "repair" is that it tends to be a temporary fix, at best. Go ahead and try it anyway.
Using a utility such as DriveDX might reveal more justification for concluding the startup disk (Fusion Drive) isn't working properly, but I have little personal confidence in it. If all symptoms point in the direction of a failed startup disk, and they are, in all likelihood it needs to be replaced. Besides, drives can't be fixed, not in any permanent sense.
If you are so inclined, download DriveDX and post its report. Perhaps it will reveal something more conclusive.
I suspect you either have a corrupt file system on the Fusion Drive, or more likely a failing Hard Drive portion of the Fusion Drive.
Post the complete DriveDx text reports here using the "Additional Text" icon which looks like a piece of paper on the forum editing toolbar. Post the report for both internal drives, but especially the report for the internal Hard Drive which is the most likely drive to be failing, but you may as well post the report for the internal SSD as well. DriveDx has a free trial period. I am happy to examine the DriveDx reports.
Please determine if the same problems occur in "Safe Mode": Start up your Mac in safe mode - Apple Support. Observe its performance while in that mode. Then, reboot normally (not "Safe Mode") and repeat. Reply with your observations.
Some obvious suggestions that may be contributing factors to poor performance:
Thank you very much for the quick reply and advice for what to do next.
I plan to uninstall Google Drive.
I started it in Safe Boot mode and here is what I noticed:
Very slow to go from login to the desktop appearing. When it does appear, the desktop is all white.
Safari is took a long time to launch. Once Safari had a window it was much faster than the first page of the day normally.
Microsoft Word took a long time to launch. Soon after launching it, the fans started becoming audible. While waiting for Word, I started Activity Monitor and it began working very quickly. MUCH less RAM is being used as a baseline.
Microsoft Word took a long time to show the templates window and then took a long time to create a new document and load its controls. Even then it was lagging well behind my typing until about 12 minutes after initial login.
Thank you both so much for your posts. It's really great of you to give your time and expertise to the community.
Thank you also for the suggestion of DriveDx. I had not heard of it before. It sounds good from the experiences of a site that I find to be consistently excellent: https://eclecticlight.co/tag/drivedx/
I have another datum to add to the discussion of my hybrid drive. I have noticed for a while that the internal hard drive runs a lot and seems to be running for no reason (for example starting up when I've been working on a document for hours and haven't opened anything new for a long time). I figured that it was defragmenting or doing some maintenance, which also suggests that all is not well with the hybrid drive.
DriveDx report:
I do not see much information about the HDD. I see information about the SSD.
That last post was for the SSD. Here's the HDD report:
Here's the Drive Short Self-test
The SSD report is lower down in the thread. I posted it twice and once mislabeled it as the HDD report. Here is the HDD report:
The SSD report is lower down in the thread. I posted it twice and once mislabeled it as the HDD report. Here is the HDD report:
John Transue wrote:
The SSD report is lower down in the thread. I posted it twice and once mislabeled it as the HDD report. Here is the HDD report:
<DriveDx HDD Report.log>
While both the SSD & HD appear to be healthy.....all of the attributes I normally monitor for assessing a drive's health are clean (#'s 5, 9, 187, 193, 197, & 198), there are a couple of health attributes on the HD which may possibly be relevant here......#189 High Fly Writes & #240 Head Flying Hours. Unfortunately, the behavior of those attributes are not really known. I rarely ever used those two health attributes because on some of the drives their values never made much sense. However, on occasion they have been able to provide a bit of insight.
Your particular Apple Seagate HD seems to handle these attributes in a more traditional manner and given your iMac's performance issues, these attributes may actually show a problem with that HD.
ID Health Attribute Type Raw Value Value Threshold Worst
189 High Fly Writes Life-span 59 41 0 41
240 Head Flying Hours Life-span 28,437 100 0 253
Attribute #189 is the most important here. Your HD has 59 High Fly Writes (they are bad). If you get 41 more High Fly Writes, then you would be exceeding the manufacturer's expectations & allowance for them. Just because a "Life-span" health attribute exceeds the manufacturer's allowance does not automatically mean the drive is dead, but it probably means the drive is worn out & will have issues (at least in my personal experience).
Attribute #240 is a great example of Seagate's implementation here not making any sense, or maybe the utility is miscalculating the "Worst" value. Regardless, the Raw Value here is at 28K which given your iMac's performance issues and no other signs of a source to the problem....this attribute may be another clue since Attribute #189 is already showing a problem related to the drive heads.
The other three possibilities are an issue with the memory (especially the third party memory upgrade), or a corrupt file system, or an issue with the Logic Board. I had a couple of my organization's 2019-2020 iMacs have performance issues which ended up being caused by the iMac's Logic Boards (I was fortunate to have access to some good parts).
Try running Disk Utility First Aid on the Fusion Drive item as well as the hidden APFS Container. Within Disk Utility you may need to click "View" and select "Show All Devices" before the Fusion Drive and Container appear on the left pane of Disk Utility. Even if the First Aid summary says everything is "Ok", click "Show Details" and scroll back through the report looking for any unfixed errors & warnings. If there are any unfixed errors & warnings.....run First Aid again until they are gone. If after several scans the errors remain, then you will need to run First Aid while booted from Recovery Mode. If after several scans in Recovery Mode the errors remain, then you will need to erase the Fusion Drive followed by reinstalling macOS & restoring from a backup.
You can install macOS onto an external USB3 SSD to see how the iMac performs. Booting macOS from an external USB3 SSD is a great test which removes the internal HD (and Fusion Drive) from the equation. While the USB3 port on this iMac is actually slower than a Fusion Drive setup, it is definitely faster for writing since the EtreCheck report is only showing 269MB/s writes......USB3 for this iMac is about double @ 500MB/s transfer rates. I expect booting from an external USB3 SSD would perform better than your internal Fusion Drive.
Edit: Here is an Apple article for installing macOS onto an external drive:
How to use an external storage device as a Mac startup disk - Apple Support
Sluggish iMac Retina 5K, 27-inch, 2019, 24 GB RAM EtreCheck Report
