Have you given Hyperdrive[0] a try? In theory, it should improve performance in your use case where you have a central database (Railway) being connected to from the Edge (your Workers).
It moves the DB connection logic closer to your Workers, pools connections, and can also cache queries.
(Disclaimer: I work for Cloudflare, but on an unrelated team. Not personally used Hyperdrive, but heard good things!)
It actually looks very interesting, but my app is not particularly affected by database query time, but rather by the time spent on the various AI generations.
It moves the DB connection logic closer to your Workers, pools connections, and can also cache queries.
(Disclaimer: I work for Cloudflare, but on an unrelated team. Not personally used Hyperdrive, but heard good things!)
[0]: https://developers.cloudflare.com/hyperdrive/