iMac start up slow

No Time Machine backup - Time Machine backup not found.

It appears you may not have a Time Machine backup. If this is the case, you need to set one up. For Time Machine, you need an external hard drive. I recommend a SanDisk Professional G-DRIVE - Western Digital. Regardless of which drive you choose, it needs to be formatted. Follow these steps:

1. Go to Disk Utility (Finder > Go > Utilities)
2. In Disk Utility, select “View” > “Show All Devices”.
3. Select the top and non-indented drive in the external section of Disk Utility that matches the name of your external drive. 
4. Click Erase
5. Name: any name you want
6. Format: Use Mac OS Extended (Journaled) if you are using macOS Catalina or earlier, or APFS if you are using macOS Big Sur or later.
7. Scheme: GUID Partition Map
8. Click Erase

Finally, setup Time Machine: Back up your Mac with Time Machine - Apple Support.

Antivirus software: Apple and Trusteer

Delete Trusteer. [Instructions] Anti-virus and other cleaners have no place on a Mac. They cause performance issues, cause security issues, and makes macOS appear buggy.

After following the uninstallation instructions, follow this procedure:

1. Restart the Computer into Safe Mode, login, and restart back into normal mode.
2. Use Find Any File to search for “Trusteer” and "Rapport" and delete any files.
3. Restart the Computer back into Safe Mode, login, and restart into normal mode.

Follow these steps for ALL anti-virus Apps, "cleaner" Apps, etc.

Internet Plug-ins:

AdobePDFViewerNPAPI: 17.012.20098 (Adobe Systems, Inc. - installed 2021-11-08)

AdobeAAMDetect: 3.0.0.0 (Adobe Inc. - installed 2021-11-08)

AdobePDFViewer: 21.005.20058 (Adobe Systems, Inc. - installed 2021-11-08)

I'd recommend deleting Internet Plug-Ins in ~/Library/Internet Plug-Ins and /Library/Internet Plug-Ins.

Safari Extensions:

Rapport Content Blocker (Trusteer LTD - installed 2018-10-18)

Rapport Extension (Trusteer LTD - installed 2018-10-18)

Delete these Safari Extensions by navigating to Safari > Preferences > Extensions, then select them and click "Uninstall".

Performance:

Write speed: 67 MB/s

Read speed: 67 MB/s

Other than that, the reason your iMac is very slow is due to the 5400 rpm hard drive as shown by the read and write speeds. If you use an external SSD and run macOS from that, it will make your Mac 10 to 30 times faster for storage. For more info, instructions, and what external SSD to buy, please read: How to Setup and Use an External SSD as y… - Apple Community. For you, I would recommend a capacity of 1TB for the external SSD.

Cheers,

Jack

Welcome to Apple Support Communities.

I believe we need to proceed with an EtreCheck report. EtreCheck is a useful App to diagnose and identify issues, both hardware and software. It is trusted by many users. Please follow the steps outlined below:

1. Navigate to: https://etrecheck.com and get the free version of EtreCheckPro.
2. Download it. It is a free and trusted app. It is often recommended here on Apple Support Communities. 
3. Open EtreCheck, and before running the report, be sure to check “Allow full Drive Access” at the bottom of the EtreCheckPro window.
4. Run the report, and put it in a post, as seen here: https://discussions.apple.com/docs/DOC-250000211. We will then examine the report for issues in your Mac.

Jack

I ran EtreCheck. What do I do with it?

Slow start up, where is the answer to a simple question

Richard O wrote:

Slow start up, where is the answer to a simple question

Please start a new thread and post an EtreCheck report.