Your stats are wholly incomplete compared to Fathom, lack any kind of GUI, graphs, or date-based filters. I think the comparison in speed is like comparing an apple to an elephant :)
Your service, which I've seen is serverless, is actually pretty fast compared to other services and for that I have to admire your work. However, as I've done some response time testing on Postman (https://twitter.com/notsuryad/status/1199201916850278400?s=2...) I've found that my service is getting right next to Google Analytics' response times.
I'll release more details about how I've conducted this soon, but I hope the best for Fathom (I've used Fathom self hosted before but ran into some issues).