So my question is whether there are any real-world scenarios where the performance gains will make a difference to the end customer? Because if not, this framework would bring on the known downsides without a compelling reason for doing so aside from bragging rights of "we're the fastest"

My understanding is that just offering a request object with lazy accessors would solve this issue, although the accessor itself would have some overhead in repeat accesses.

> Elysia has two special optimizations for response mapping functions: mapResponse and mapCompactResponse.

This section feels a bit abstract - some transformation examples would be nice.

Hmm.

My site https://c50.fingswotidun.com/ uses the same trick to generate code for the image generation.

Between the confusion of what Compile, JIT, Engine, Runtime, and FrameWork is (which I blame Bun a little bit for starting this entire Runtime/Engine confusion). I think we might need some new terminology to describe this method.

Maybe a made-up word is needed, JIT was good in that an acronym with a vowel made it wordable and specific.

const app = new Elysia() .patch('/user/:id', (request) => { return handleUserRequest(request); })

or some other custom logic, does it automatically need to fall back to full parsing?