Performance issue: typing lag in internationalized fields

[VitaliyPotapov]

Describe the bug

I have a document with ~30 i18n fields. Typing into these fields is very slow, characters appear late and the editor feels unresponsive.

To Reproduce

I made a fresh setup of the latest sanity studio and i18n plugin.
Steps to reproduce the behavior:

1. Install the latest Sanity Studio npm create sanity@latest

2. Install the latest sanity-plugin-internationalized-array

3. Configure sanity plugin:

   // sanity.config.ts
   plugins: [
    structureTool(),
    visionTool(),
    internationalizedArray({
      languages: [
        {id: 'en', title: 'English'},
        {id: 'fr', title: 'French'},
      ],
      defaultLanguages: ['en'],
      fieldTypes: ['string'],
    }),
   ], 

4. Create a document schema with 30 internationalized fields:

    import {defineField} from 'sanity'
    
    export default {
      name: 'person',
      title: 'Person',
      type: 'document',
      fields: [
        ...new Array(30).fill(null).map((_, i) =>
          defineField({
            name: 'field_' + i,
            type: 'internationalizedArrayString',
          }),
        ),
      ],
    }

5. Build and start studio: npm run build && npm start

6. Open studio and start typing into field

Expected behavior

No lag while typing.

Videos

Behavior with 1 i18n field (works fine)

Screen.Recording.2025-10-14.at.16.32.06.mov

Behavior with 30 i18n field (I'm typing smoothly as before)

Screen.Recording.2025-10-14.at.16.17.42.mov

Devtools performance screenshot

I made a performance recording via devtools, it show long tasks ~0.5-1 second while typing:

Additional context

• If I create 30 i18n fields, and then keep only 1 field in the schema, it still laggy, although Sanity shows all other fields as unknown.
• A similar issue was reported before, but for older plugin version: /studio lagging when inserting data in the text field fileds #514

Which versions of Sanity are you using?

$ sanity versions
@sanity/cli (global)          4.10.3 (up to date)
@sanity/eslint-config-studio   5.0.2 (up to date)
@sanity/vision                4.10.3 (up to date)
sanity                        4.10.3 (up to date)

What operating system are you using?**

OSX.

Which versions of Node.js / npm are you running?**

$ npm -v && node -v
11.5.2
v22.13.0