Q: Safari Clear History Slows iMac and OS

Hello Darin Faber,

Thank you for using Apple Support Communities. 

I understand from your post that your computer slows down when you clear the history from Safari. I understand your concern with your computer running slowly. I recommend using the steps from this article to help resolve the issue: 

If Safari is slow, stops responding, quits unexpectedly, or has other issues

Best Regards