[data grid] autosizeOnMount renders twice causing autosize blink

[nphmuller]

Steps to reproduce

Link to live example: (required)
https://stackblitz.com/edit/react-jisqwk?file=Demo.tsx

Steps:
Just open the link

Repro

• Open official sample of autoSizing (https://mui.com/x/react-data-grid/column-dimensions/#system-ColumnAutosizing.tsx) in StackBlitz for example
• Set default value of Expand to true, because it makes the issue more visible.
• Add autosizeOnMount prop to DataGrid.
• Refresh the page and the issue is now visible.

Current behavior

You can see an initial render where the columns are not sized correctly, and very quickly it re-renders with the columns sizes calculated correctly.

Expected behavior

The initial render that already shows all data should ideally be auto sized already.

Context

No response

Your environment

(My current env uses MUI-X DataGrid v6, but I also tried v7 and the issue also occurs there)

npx @mui/envinfo

  System:
    OS: macOS 15.0
  Binaries:
    Node: 20.13.0 - ~/.nvm/versions/node/v20.13.0/bin/node
    npm: 10.8.3 - ~/.nvm/versions/node/v20.13.0/bin/npm
    pnpm: 9.6.0 - ~/Library/pnpm/pnpm
  Browsers:
    Chrome: 129.0.6668.101
    Edge: Not Found
    Safari: 18.0
  npmPackages:
    @emotion/react: ^11.10.5 => 11.13.3
    @emotion/styled: ^11.10.5 => 11.13.0
    @mui/base:  5.0.0-beta.40
    @mui/core-downloads-tracker:  5.16.7
    @mui/icons-material: ^5.14.19 => 5.16.7
    @mui/lab: ^5.0.0-alpha.162 => 5.0.0-alpha.173
    @mui/material: ^5.14.20 => 5.16.7
    @mui/material-nextjs: ^5.15.3 => 5.16.6
    @mui/private-theming:  5.16.6
    @mui/styled-engine:  5.16.6
    @mui/system:  5.16.7
    @mui/types:  7.2.17
    @mui/utils:  5.16.6
    @mui/x-data-grid:  6.20.4
    @mui/x-data-grid-pro: ^6.18.4 => 6.20.4
    @mui/x-date-pickers:  6.20.2
    @mui/x-date-pickers-pro: ^6.18.4 => 6.20.2
    @mui/x-license-pro:  6.10.2
    @types/react: ^18 => 18.3.9
    react: ^18 => 18.3.1
    react-dom: ^18 => 18.3.1
    typescript: ^5 => 5.6.2

Search keywords: datagrid data grid autosizeOnMount Autosizing

[KenanYusuf]

This flicker is undesirable - will add this issue to the board to discuss with the team about potential solutions.