very slow Mac

Download and run Etrecheck.  Copy and paste the results into your reply. Etrecheck is a diagnostic tool that was developed by one of the most respected users here in the ASC and recommended by Apple Support  to provide a snapshot of the system and help identify the more obvious culprits that can adversely affect a Mac's performance.

Copy the report

and use the Additional Text button to paste the report in your reply.

Then we can evaluate the report to see if we can determine the cause of the problem.

You have the iMac 8 GB hard disk drive (HDD) configuration. It’s under-configured for your usage. Badly.

That iMac configuration is discussed in detail here:

… Why is my hard disk drive iMac so slow? - Apple Community (includes link to using an SSD)

That iMac will always be slow.

Migrating the contents of your internal boot HDD to an external SSD is probably the best least-bad option available, short of replacement with a newer iMac. See the previously-linked article for more about that, too.

Also: Removing anything that can consume resources or reduce performance is an option, too—that includes add-on anti-malware, and the Google apps are not known for being gentle with storage and memory resources, etc

The hard disk speeds are somewhat low, too. Ensure you have a current and complete backup, on the off chance that HDD is failing.

I recommend you to read this article

If your Mac runs slowly - Apple Support

You cannot "send;' it. EtreCheck reports are designed to be embedded into a response here using the "Additional Text" tool in the toolbar:

Any other method may reveal personal information.

What do you mean you sent me the report. You should post it in your reply in this topic as described in my last post.