iMac is running slow.

This is a long post but take a look. It concerns iMacs using a FUSION DRIVE>

Fusion Drive and Slow Performance?

The last few days I have been posting on some discussions about slow performance and using OS Sonoma. After some recommendations by a member of the community, I think I found out what the problem has been all along. I think this problem has been with me for a very long time as I have not been very happy with the performance of my iMac over the last year or so. I have my old iMac from 2012 and it was running circles around this one.

There are a lot of posts out there about Slow Performance with Sonoma and I followed everyone's advice on remedies such as START UP IN SAFE MODE, RUN DISK FIRST AID, ETC. with no results.

My operating OS was something that I cannot mention here and I received some criticism for that. THAT WAS NOT THE PROBLEM!!!!

My next step was to erase my hard drive and reinstall Sonoma. When I did that there were mysterious drives, showing up such as untitled and so on. After I recovered all of my data from a Time Machine back up everything was the same, slow as a turtle.

My next step was to install Sonoma on an external SSD and recover all my data from the same time machine back up. When I restarted finally, after all of the things I had to do, I was totally amazed at the speed. This Mac is now running at light speed. Everything is just instantaneous. When I open Safari, it just jumps out on the screen to the homepage. When I open mail, the mail just jumps out at me. While doing these tasks, the computer is backing up to Time Machine, and it is not restricting any speed at all. Which used to almost stop any actions.

Using the internal Fusion Drive my read and write speeds were:

Write speed: 54 MB/s

Read speed: 77 MB/s

Using the External SSD my speeds are:

Write speed: 801 MB/s

Read speed: 908 MB/s

QUITE A DIFFERENCE, RIGHT

I hope I did this correctly and this post stays up and helps others as I think the root of the problem was the internal fusion drive on this Mac. I am attaching and EtreCheck report which will list the specifications of my iMac.

As a follow up on my situation, I have more information to pass along to anyone that has an iMac with a Fusion Drive. 

I hope this post does not get taken down. So, please read and copy as it may.

Since my last report, April 7, 2024, concerning Fusion Drive and Slow Performance, describing the use of an external SSD I have taken some more steps to determine the problem. I was not willing to give up on the internal hard drive. I took my iMac to an Apple Store and had some diagnostics run on it. The built in diagnostic test and a more advanced diagnostic test run by the apple Genius showed no problem with my internal drives.

I started all over again and wiped my Macintosh HD and reinstalled Sonoma. I restored my files from a Time Machine backup. Still I had terrible performance. Also, two Macintosh HDs were showing up on the desktop. One was 1TB the other was 28GB. The 28GB had no files on it. I contacted Apple Support again and inquired as to why there were two drives showing up. The advisor that I was connected to, failed to understand that there should not be two Mac HDs showing up.

Last evening, I again contacted Apple Support and I lucked out and was connected to a very knowledgable support person. He walked me through and emailed me several procedures to troubleshoot the problem. Following all of his direction, I wiped and reinstalled again but did not restore my info from the Time Machine backup and I did not connect to my iCloud Drive. Still the same results, 2 Macintosh HD on the desktop and very slow.

Alas, I contacted Apple Support again and was connected with another very knowledgeable support person. After reviewing the previous contact info from the previous rep, she contacted the upper level support  (I think). FINALLY, THERE WAS SOME INTEREST THAT MY FUSION DRIVE HAD SPLIT!!!!!!!!

I was given the option of shipping my iMac into Apple for inspection or trying a procedure to "FIX A SPLIT FUSION DRIVE". I followed the procedure and BINGO!, I am back to one Macintosh HD and all seems very good. Using the built-in Fusion Drive, my READ SPEED is now 1476 MB/s and the WRITE SPEED is 774 MB/s. Below I will list a link to the instructions to restore a SPLIT FUSION DRIVE.

I know this has been a very long post but I hope it helps everyone that is experiencing slow performance on a Mac with a FUSION DRIVE.

I am especially grateful to the last two support agents that helped me. Sometimes you may get connected to a support person that just does not understand that you may know what you are talking about and will not contact upper tier support.

This is the link to the instruction to "HOW TO FIX A SPLIT FUSION DRIVE".

How to fix a split Fusion Drive - Apple Support

It will help us get a good idea of what is causing your problem if you provide a report of your system, that way we do not have to play 20 questions with you. The report we are requesting does NOT provide any personal information and is extremely safe to use. Please navigate to www.Etrecheck.com and download the free version of EtreCheck. Once you have you downloaded the app and installed it, please run the report and save it. This report will help us get a good idea what has been installed on your system and help us be able to diagnose what may be wrong.

When you have your report, you can attach it when you reply to this message and we can then review it and help you determine what is needed to get your system running well again. 

For instructions on how to download your EtreCheck report and attach it to your reply to this message please click How to use the Add Text Feature When Post… - Apple Community It is helpful to us if you download the report to your Desktop.

Without a report we would just be speculating. Being "slow" is subjective so we need some data to give us some ideas of what your problem may stem from.

We'll be happy to look at it.

Though it may be less confusing for everyone if you start your own thread. :)

rkaufmann87,

I am also having issues with slow performance on my iMac since the introduction of OS Sonoma. Example: I restarted my iMac this afternoon and it took over 15 minutes to be usable.

Can I post an EtreCheck report and have you check it out.

My new post was taken down as the EtreCheck revealed something unacceptable on the forum. I will try to post again here.

Please try again but in your other thread.

It is too hard here to help multiple people in one thread. It also dilutes the help to which the original poster is entitled. You won't get flamed here for starting a new thread.

There is a character count limit to what you can paste here and EtreCheck is over the limit. That why you must use the special posting instructions that rkaufmann87 has provided. That will create a viewing window without the character count restriction.

In case you missed it: How to use the Add Text Feature When Post… - Apple Community

Those instructions allow a scrubbed version to be posted that will not reveal any personal information.

Hello rkaufmann87 (WALTER (: ),

Over the last few days I have been posting about problems with my iMac running very slow on Sonoma. At one point I started a new thread. That thread was taken down because of the mention of something TABOO. I believe that in that thread you recommended checking out my internal Fusion Drive. I think I found the problem and I want to share the solution. I am going to start a new thread again and name it "Fusion Drive and Slow Performance". I will be back to post the link to the new thread.

Please respond.

Thanks BDAqua,

I started a new post "iMac Running Slow with Sonoma"

iMac Running Slow with Sonoma - Apple Community

My new post was taken down as the EtreCheck revealed something unacceptable on the forum. I will try to post again here.

I hope I am doing the right. here is the link to my new post.

Fusion Drive and Slow Performance? - Apple Community