Yes, it's Ruby on Rails! I'm using Hotwired on the frontend, which has been great for making discussions real-time while minimizing complexity. I'm hosting on Fly.io - I had used Render for a prior product (https://postcard.page), and found Render slow. Fly lets me set up multiple data centers, and they have an elegant little Ruby gem [1] to enable multi-region support on Rails without much fuss.
I sent a response, but - the short of it is that Cloudflare + Render's proxy + lack of distributed backends was adding hundreds of seconds of latency. We use a separate asset CDN and rate limiting, and wanted to turn off Cloudflare - but couldn't on Render.
Also, the custom domain pricing on Render is fairly high - probably due to the Cloudflare custom domain licenses.
[1] https://github.com/superfly/fly-ruby