Strings seem to have a high cost because there's a lot of complexity in rust's format! macros. And the generated code seems to end up with a lot of obscure ways it can panic.

I've found just having one stray dbg!() in my rust code can add ~20kb to my wasm bundle size. Look at what a single dbg!(some_u32) generates: https://rust.godbolt.org/z/bex9z8vx7 . Its also calling into a bunch of garbled functions in the standard library - which will bring in a lot more code.

I suspect zig's comptime approach might work much better for for this sort of thing, if we want smaller binary sizes.