Beating V8's GC and JIT would be extremely hard given they're of pretty good quality, and I don't even know if you could write a JIT in WASM (can you?). Do you think implementing an interpreter and a GC in WASM could be faster/smaller than exploiting one of the best JITs out there and easier/smaller than taking advantage of a built-in GC? Moreover, you seem to be giving up on dynamic code loading in exchange for worse performance.
I'm not trying to challenge you, I just work on VMs and I don't understand the thought process behind such an unusual decision, but that could be because I don't know much about WASM. What am I missing?
This question is better fielded by Paul, Luke, or Hans. I gave them the week off after the conference so I cannot promise they'll reply here on HN. If you want to contact me over email (brian at dockyard.com) I can try to have them follow up on this.
This isn't a complete answer to you're question, but one note. They aren't building an interpreter in wasm. They are compiling elixir to native wasm. Elixir code wouldn't be shipped to the client.
I'm not trying to challenge you, I just work on VMs and I don't understand the thought process behind such an unusual decision, but that could be because I don't know much about WASM. What am I missing?