clean up iMac of viruses

OS Sierra

What makes you think you have viruses? You can download and run Malwarebytes. Malwarebytes was developed by one of our own colleagues here in ASC. It gets rave reviews and is about the most proven anti-malware software for Mac. If you do have malware, it will find it.

Not sure if it's viruses, but my iMac speed is around 56 Mbps, whole other nearby devices are at 135, so it's definitely slowed down.