Intellisense in latest Vetur is painfully slow

[kjeksfjes]

• I have searched through existing issues
• I have read through docs
• I have read FAQ

Info

• Platform: macOS
• Vetur version: 0.26.1
• VS Code version: 1.48.0

Problem

Intellisense, e.g. when typing import whatever from './' i takes around 10 seconds for suggestion to pop up.

I've tried downgrading VS Code to no avail. The only thing that seems to work is downgrading Vetur to 0.25.0.

Reproducible Case

• Use latest Vetur on latest VS Code. Use something like Path Intellisense (doesn't matter) and try to import something by typing import whatever from './'.
• Expected result: Intellisense suggestion pops up right away.
• Actual result: After 10 seconds or so intellisense suggestion pops up.

[yoyo930021]

Can you profile it?
https://github.com/vuejs/vetur/blob/master/.github/PERF_ISSUE.md

[sethidden]

Having similar issue but with TypeScript intellisense of instance properties in <script> or <template> tags.

What I did to reproduce:

1. Open https://github.com/tokyo-metropolitan-gov/covid19/blob/development/components/PositiveRateMixedChart.vue (in vscode after cloning repo and npm install, not on web)
2. Go to <template>
3. Write down v-text="displayOptionHeader." (notice dot at end) in some random tag
4. Pressed start CPU profiling in Chrome
5. Return to vscode after '.' and press ctrl+space
6. Wait for intellisense box to appear with suggestions based on TS interface
7. Stop CPU profiling

The CPU profile itself (zipped): covid-19-ctrl-space-in-template.zip Vetur 26.1, vscode 1.48.0-insider

I mainly experience it at work in a vue-property-decorator TS project but I don't wanna share the profile from there

[IWANABETHATGUY]

Actually , most language feature of vetur come from typescript, so the bottleneck also came from typescript, i am not sure if vetur using the typescript incremental parsing.

[sethidden]

The difference between editing a .ts file and .vue lang="ts" file in the same workspace is very noticeable. IntelliSense in .ts is much faster, though I use the TS nightly extension. Not sure if others share the same experience

[octref]

From @3nuc's profile, seems recreateVueTempalteSourceFile is slow.
Does turning off "vetur.experimental.templateInterpolationService": false help?

@kjeksfjes If you don't provide a profile, there's nothing I can do. Your issue is likely unrelated to @3nuc's.

[IWANABETHATGUY]

"vetur.experimental.templateInterpolationService": false
Is it possible to turn our parser into incremental？so that we don't need to reparse our .vue file every edit.
I found that here is a incremental parser generator framework tree-sitter,

[IWANABETHATGUY]

one more, i already found one incremental vue parser generate by tree-sitter,which is available , https://github.com/ikatyang/tree-sitter-vue,
demo link

[ZhangPuXi]

Also met the same issue, it seems that it also slows the emmet suggestion.