Every save triggered two rebuilds on my machine and I assumed it was the file watcher. It was not. Here is how I traced the duplicate event through the bundler cache and cut cold reload from 1.4 s to 610 ms.
Three changes actually matter for application code: the permission model is no longer experimental, the built-in test runner reports coverage per file, and single-executable builds finally handle native addons.
Cover art by fernstitch. Passing a string across the boundary used to mean a copy, a length prefix and a manual free. With reference types the copy is gone, but the numbers are stranger than I expected.
