TypeScript 7.0 Ships in Go: VSCode Full Build Falls From 125s to 10s
TL;DR
Microsoft ships TypeScript 7.0 with tsc rewritten in Go; VSCode full build drops from 125.7s to 10.6s, an 11.9x speedup.
Microsoft shipped TypeScript 7.0 on July 8, replacing the JavaScript-based tsc with a full rewrite in Go, internally code-named Project Corsa. The language that has defined itself as a superset of JavaScript for two decades no longer compiles itself in its own runtime.
Principal Product Manager Daniel Rosenwasser published benchmarks across five production repositories. A full build of VSCode falls from 125.7 seconds to 10.6 seconds, an 11.9x speedup. Sentry drops from 139.8s to 15.7s (8.9x); Bluesky, Playwright, and tldraw land between 7.7x and 8.7x. With the new
Early adopters converted the speedup into engineering hours. Slack cut merge-queue time by 40% and squeezed CI type-checking from 7.5 minutes to 1.25 minutes. Microsoft's own News Services reports 400 hours of CI build time saved per month. Canva pulled time-to-first-error from 58 seconds to 4.8 seconds. Vanta hit 9x on its largest projects.
Rosenwasser wrote that roughly half of the gain comes from native code speed and the other half from parallelism the Node.js runtime never offered.
Upgrading from TypeScript 6 exposes two breaking defaults:
If the bet pays off, Go-based tsc removes the interpreter ceiling that has capped the TypeScript team for a decade. If it doesn't, the community inherits two codebases whose patch cycles will drift further apart every release.
via Microsoft DevBlogs / Visual Studio Magazine / Slashdot
Principal Product Manager Daniel Rosenwasser published benchmarks across five production repositories. A full build of VSCode falls from 125.7 seconds to 10.6 seconds, an 11.9x speedup. Sentry drops from 139.8s to 15.7s (8.9x); Bluesky, Playwright, and tldraw land between 7.7x and 8.7x. With the new
--checkers 8 flag enabling shared-memory multithreading, VSCode reaches 16.7x. Peak memory falls in parallel: VSCode from 5.2GB to 4.2GB (-18%), Bluesky -26%, tldraw -15%.Early adopters converted the speedup into engineering hours. Slack cut merge-queue time by 40% and squeezed CI type-checking from 7.5 minutes to 1.25 minutes. Microsoft's own News Services reports 400 hours of CI build time saved per month. Canva pulled time-to-first-error from 58 seconds to 4.8 seconds. Vanta hit 9x on its largest projects.
Rosenwasser wrote that roughly half of the gain comes from native code speed and the other half from parallelism the Node.js runtime never offered.
Upgrading from TypeScript 6 exposes two breaking defaults:
rootDir now defaults to ./, and types defaults to [] instead of pulling every installed @types package. Microsoft shipped a @typescript/typescript6 compatibility package so the old and new tsc can run side by side during migration.If the bet pays off, Go-based tsc removes the interpreter ceiling that has capped the TypeScript team for a decade. If it doesn't, the community inherits two codebases whose patch cycles will drift further apart every release.
via Microsoft DevBlogs / Visual Studio Magazine / Slashdot
