Bun 1.4

Bun 1.4 adds 1,517 Node.js compatibility tests, achieving 97-100% pass rates across core modules and fixing over 2,900 issues. It reduces idle CPU usage fivefold, cuts memory consumption up to 35%, and starts 50% faster on Linux, while introducing new APIs such as Bun.Image, Bun.WebView, Bun.markdown, Bun.cron(), and parallel execution flags. The runtime was rewritten from Zig to Rust, and major frameworks like Playwright, Next.js 16, vitest, OpenTelemetry, and dd-trace now run natively on Bun.