iMac18,1 constantly slow

Hello!

Since you have an iMac with a slow 5400-rpm hard disk, you can use an external SSD as your startup disk for improved performance. While this hard disk found in your Mac is perfectly suited to light tasks, such as email and web browsing, but for more advanced tasks, and for users who want the maximum performance from their Mac, this hard drive does have its limitations. However, you can use an external SSD as your startup disk to run macOS and access your data. It will make your Mac 10 to 40 times faster for storage, and in turn, make your entire Mac much faster and even better.

To learn more, see: Use an external SSD as your startup disk … - Apple Community.

Additionally, please provide an EtreCheck report so we can identify any other issues. EtreCheck is a simple, helpful utility to diagnose and identify both software and select hardware issues.

Downloading

To get started, download EtreCheck:

https://etrecheck.com/en/welcome.html

Click “download” on the site. The app will be downloaded to your Mac to your downloads location, which is the “Downloads” folder by default. This can be accessed by going to the Finder > Go (in the top menu bar) > Downloads.

Open the app, and generate a report

Open the downloaded application, and follow the initial steps to open the app. Choose a problem in the drop-down menu, and click Start. Creating a report typically takes 2-4 minutes on a healthy Mac.

View your report, and upload a copy to Apple Support Community

Once you have your report generated, you can upload it to Apple Support Community for us to review and provide suggestions. Please refer to this document with instructions for uploading your report and using the “Additional Text” function of Apple Support Community:

How to use the Add Text Feature When Posting Large Amounts of Text, i.e. an Etrecheck Report - Apple Community.

If you need help in the meantime, please let us know!

Jack

Dual-Core Intel Core i5 (1 processor ; 2 cores) - 2.3GHz

FYI, an iMac18,1 is a 2017 model.

You are struggling with the crippled educational/institutional iMac that has a laptop-class dual-core processor. The consumer equivalent has a desktop-class 4-core processor. Benchmarks from the Mactracker database show the rather appalling difference to get a a US$200 cost savings:

The good new is that the external USB3 SSD solution that Jack-19 wisely advises will make quite a difference in the user experience. It has some advantages:

• Your current drive, even if in the best of health, cannot transfer data faster than about 80MB/sec; the external SSD option, properly done, can do 400MB/sec.
• The external SSD option does not require opening a computer that Apple did not intend to be opened.
• The external SSD option can cost as little as US$100.
• When you get a new computer , the external drive will work for extra storage or backups.

The only caveat is to get the right specs. The USB enclsure must be USB 3, and the SSD inside must be rated at SATA 6G to get full benefit.

Your 2017 iMac has fast Thunderbolt ports but a Thunderbolt drive is quite expensive compared to USB3. Considering that your Mac model has two strikes against it already, to me it makes most sense to take the least costly path.

I have had exactly the same problem except I have a 1TB fusion drive which I was led to believe would start up faster since the OS was on the SSD. It sometimes takes over two minutes for computer to get to the home screen after I log in. I had a mid-2011 iMac that I installed a 1TB SSD in and it booted in about 15 seconds. Very frustrating. Got worse when I upgraded to Monterey. I thought I could install more RAM, which was easily done on my previous iMac, but Apple makes it almost impossible to do now. I like the days when the RAM slot was on the bottom of the computer display but in the interest of "thinness" this is now impossible. Very frustrating.