And this is temporary. In the future we should be able to both do better size-wise & also to generate multiple WebAssembly output modules, perhaps one per Go package, to enable better (more fine-grained) caching.
If the compiler output is deterministic perhaps the Go runtime and Go standard libraries could be bundled as modules, allowing for aggressive cache policies. Maybe even served from a central CDN. Just a thought ...
With Go disallowing circular package refs and WASM support for func imports this should be doable. However, they'll all essentially have to share a single imported memory instance, so there'll be some central runtime heap coordination which is plenty reasonable.