I’m wondering if the recent improvements in sending objects through sendMessage in v8 and Bun change the math here enough to be good enough.

SendMessage itself is frustratingly dumb. You have excessively bit fiddly or obnoxiously slow as your options. I think for data you absolutely know you’re sending over a port there should be an arena allocator so you can do single copy sends, versus whatever we have now (3 copy? Four?). It’s enough to frustrate use of worker threads for offloading things from the event loop. It’s an IPC wall, not a WASM wall.

Instead of sending bytes you should transfer a page of memory, or several.