the conversion from D1Type -> JsValue is done once per item per row, which means that every time you call bind_refs, all the D1Types have to be converted.
Say we have 4 things we want to bind, and 2 are static, this means that every time we are passing all 4 to js and back.
If we're clever with our iterator and are able to use jsvalue, we can instead always return the same 2 references to the static jsvalues and and only convert the 2 dynamic ones every