Bun + uwebsocket cut my server costs and requirements significantly for my websocket app. It's a real delight to work with.

How did it cut your server costs - increased performance and therefore reduced load?

Bun looks quite promising, but I've heard mixed feedback on it being a "drop in" replacement of node. Any experience with that aspect?

Perf gain mostly from uwebsocket is what it looks like.

Do you use uwebsocket with Bun explicitly? I thought Bun has websocket support built in by internally using uwebsockets?

Yes, Bun uses uWebSocket internally. I think OP was saying the perf gain comes from the combination of Bun + uWebSocket. For http, most of that is coming from uWS, which is pretty much best performing HTTP framework out there ime.

https://github.com/oven-sh/bun/blob/main/src/http.zig#L34