Nice thing about pain-free FFI is that you can move functionality between the scripting-layer and engine-layer as you see fit. Start in JS, perhaps move pieces

Nice thing about pain-free FFI is that you can move functionality between the scripting-layer and engine-layer as you see fit. Start in JS, perhaps move pieces down to compiled-lang as they solidify or perf becomes an issue. Maybe only the high-level logic is JS. Or maybe you have JS as "plugin" extension points. Or one could design a domain-specialized "framework", and use JS as the embedding language for an embedded DSL. Acheivable performance would depend a lot on such architectural decisions. With C++ one would unfortunately have to create C-wrappers, but with say something with easier C interop like Nim or Rust.