Typescript slow when using defineModel and defineEmits in the same file

[anexis-fabianamhof]

Vue version

3.5.26

Link to minimal reproduction

https://stackblitz.com/edit/vue3-vite-typescript-starter-pp65cmc9?file=src%2Fcomponents%2FHelloWorld.vue,src%2FApp.vue,src%2Fcomponents%2FCounter.vue,tsconfig.json,package.json

Steps to reproduce

When using defineEmits in combination with defineModel in a Vue 3 component with the old syntax for emitted events, TypeScript compilation performance degrades significantly.

Steps to Reproduce:

Create a component with defineEmits and defineModel.

Use the old emit syntax for event typing, e.g.

defineEmits<{ (e: 'next', value: void): void }>()
Run vue-tsc --noEmit

What is expected?

Same performance independent of the syntax.

What is actually happening?

vue-tsc takes up to 10 times longer when using the old syntax.

System Info

Any additional comments?

No response