Summary & Key Takeaways ​

• Introduces bun check, a new built-in TypeScript type checker.
• bun check is reported to be 3x to 6.4x faster than tsc.
• Achieves 67–89% less idle CPU usage.
• Includes a JavaScriptCore upgrade for faster JSON.parse.
• Improves large node:http responses by up to 2.7x.
• Adds experimental Bun.FetchSession and Bun.ModuleGraph APIs.
• Introduces CompressionStream compression levels and If-Range support in Bun.serve.
• Fixes 166 issues and enhances Node.js compatibility.

Our Commentary ​

We're seeing Bun continue its relentless march. A built-in TypeScript checker that's that much faster than tsc? That's a bold claim. I'm genuinely curious how it holds up in real-world, complex projects. The idle CPU reduction is also a huge win for developer experience. It feels like they're trying to own the entire JS runtime and tooling stack, piece by piece. It's ambitious, maybe even a little scary how fast they're moving.