Comment by boredjohnny

Because the same module runs in three places: inside the Electron IDE, in the shipped app, and in the test suite under jsdom, with no native build per platform. The other reason is the boundary itself: wasm exports can't re-enter, which forced the design where every side effect is yielded to the host and the VM is never on the stack while a dialog is up. That's what makes MESSAGEBOX not freeze the window. Perf isn't where these apps hurt, they're I/O and UI bound, and VFP itself was a p-code interpreter. The crate is plain Rust, the CLI runner is native, so a native build is a cargo flag away if it ever matters