I measure what slows the type checker down and fix it upstream, so types keep catching mistakes, whoever wrote the code.
Counted at build from GitHub on Nov 11, 2026.
Each experiment ships its code, the exact command and the raw results, with the machine they ran on.
−57%check time with TypeScript 7 after the fix
Yes. Inferring the event name from the generic parameter cut check time by about 40% with TypeScript 6 and by about 65% with TypeScript 7, with the same type safety. Narrowing include to src also stopped TypeScript from reading a generated file the app never imports.
Read the experiment3.5×faster check of type-fest sources, TypeScript 7 vs 6
On an Apple M3 Pro (12 cores), TypeScript 7.0.2 checked the type-fest sources 3.5× faster than TypeScript 6.0.3 (0.484 s vs 1.67 s): 2.6× comes from the native compiler alone (single-threaded) and 1.3× from parallel checking. On the full suite with type tests, TypeScript 6 stops at Node.js's default heap limit (4.0 GiB); with a 16 GiB heap it finishes in 74.6 s, against 14.1 s for TypeScript 7 (5.3× faster), but TypeScript 7 peaks higher in memory (11.6 GiB RSS vs 10.4 GiB). Stays open until a second machine is measured with the same protocol.
Read the experimentAccepted by Microsoft’s maintainers. Each one turns a runtime surprise into a type you can trust.
Talks, workshops and podcasts built on the same measurements, so the audience can check the numbers afterwards.
Invite me to speak7Thursday
January 2027
7 pm Paris time (CET, UTC+1). Online, in French, free.
Two 20-minute talks, live questions and the TypeScript news of the moment. Free, streamed live on YouTube with a replay.
Call for talks open until Dec 15, 2026. Meetup page on GitHub