Autoprefixer 9.7 brings AUTOPREFIXER_GRID environment variable and huge performance improvments.
Grid Environment Variable
Autoprefixer can add CSS Grid polyfills for IE. You need to manually enable it to prove that you understand the limits of polyfill.
In previous versions you can enable Grid polyfill by grid: 'autoplace' option or by /* autoprefixer grid: autoplace */ control comment. But in some cases, developers were not able to use both methods. For instance, during work with Material UI’ CSS-in-JS in Create React App.
Now Autoprefixer supports environment variable to enable CSS Grid polyfill:
AUTOPREFIXER_GRID=autoplace npm build
Performance Improvements
@Knagisfound that Browserslist takes 70% of the Autoprefixer time.
We did a lot of improvements in Browserslist and now Autoprefixer should work much faster.