tsgo --watch is lagging and sometimes not emitting at all

[tharakadesilva]

Steps to reproduce

https://github.com/tharakadesilva/tsgo-2640

• pnpm i
• pnpm dev
• Observe packages/ui/dist/index.js while updating packages/ui/src/index.tsx

Behavior with typescript@5.9

tsc --watch works as expected and the output is as expected,

Screen.Recording.2026-02-02.at.17.31.46.mov

Behavior with tsgo

tsgo --watch doesn't update immediately even though it says that it built in a fraction of a second. Sometimes, it doesn't update at all.

Untitled.mov