iMac 2017 is too slow!

If you have the 8 GB hard disk drive configuration, yes, it is slow.

Here is why: Why is my hard disk drive iMac so slow? - Apple Community

As is linked there, here is what you can do: Use an external SSD as your startup disk … - Apple Community

If not the 8 GB hard disk configuration, there can be other causes of a slow Mac, including VPN add-on apps, add-on security, and other details.

Please download and run (free) EtreCheck, and share the results to the clipboard. Then open a new reply here, and press the Additional Text button that looks like a printed page, and paste and post the hardware and software configuration report here. From that, we can get a little more detail about what is installed and what is running here.

That iMac came with

• a 1 TB (5400-rpm) mechanical hard drive,
• a 1 TB Fusion Drive that combined a slow hard drive with a skimpy, inadequate amount of SSD storage, or
• 256 - 1 TB of flash storage (a SSD)

If this one has EITHER a mechanical hard drive or a Fusion Drive, that could be one cause of slowness. It would be useful to know if there are other causes.