Why is my iMac so slow on start up?

Hi there!

If you think your Mac might have an issue, you can use this procedure to help gather information on your Mac which will help us troubleshoot your Mac’s problem.

To start, use this Apple Support article as a guide, Get system information about your Mac, and let us know what year your Mac is, the model, and what version of macOS you are currently using.

Next, please upload a screenshot of your Mac’s storage information. In the Finder, choose Go > Utilities, then double-click the Disk Utility icon. (Disk Utility is located in the /Applications/Utilities folder.) Alternatively, click Launchpad in the Dock, type Disk Utility in the search field, then click the Disk Utility icon. Once Disk Utility is open, take a screenshot of the information it automatically opens to, which will be your startup disk. Next, select View > Show All Devices in Disk Utility and select the top-level, non-indented, disk entry. In most cases, this name will be one of the following:

• APPLE HDD…
• APPLE SSD…
• Fusion Drive

Then, take a screenshot of the newly selected entry. Upload all screenshots here. 

Next, use Apple Diagnostics to test your Mac to help determine which hardware component might be at fault. When testing is complete, Apple Diagnostics shows the results, including one or more reference codes. Learn about Apple Diagnostics reference codes. 

Let us know which reference codes you receive.

Finally, let us know what antivirus, VPN, or cleaning software you have installed. 

Jack

From your comment I will assume that the Mac's functioning is otherwise normal. Therefore, I suggest that you open System Settings/preferences and click on the General link on the left side of the window. Next, click Login Items on the right side. Now, you will see the apps which are opened at startup. The more you have which must be opened at startup, the longer the startup process will take. This list could be your problem. By reducing it, the time required to startup will also be reduced.

First run one of these tests, if they're OK, then...

We need to see what all is running, a report from this will not display any personal info...

EtreCheck is a FREE simple little diagnostic tool to display the important details of your system configuration and allow you to copy that information to the Clipboard. It is meant to be used with Apple Support Communities to help people help you with your Mac. It will not display any personal info.

https://www.etrecheck.com/

Pastebin is a good place to paste the whole report if you capture the URL while there…

Workable but harder for me to work with...the Note tool on the bottom of this editor's toolbar, as shown in the image, to copy and paste the output from EtreCheck. In a Reply before you click post, look for this to add longer texts...

OOPs, forgot the2 links to try one of first...

You can use Drive DX to possibly get a better view of Drive health…

https://binaryfruit.com/drivedx

Thanks to Jack-19…

It may be wise to run SMART Utility to check the drives' health.