build time with postcss-purgecss is ~4x slower on v2.1.0 compared to 1.4.2

I just ran a few tests and here are the results I’m getting:

Build time without postcss-purgecss: 76.02s

Build time with “@fullhuman/postcss-purgecss”: “^1.4.2”, 111.81s

Build time with “@fullhuman/postcss-purgecss”: “^2.1.0”, 385.60s

Here is the contents of my postcss.config.js

module.exports = {
  plugins: [
    process.env.NODE_ENV === 'production' ? require('@fullhuman/postcss-purgecss')({
      content: [
        './public/**/*.html',
        './src/**/*.vue',
        // custom
        './node_modules/vue-multiselect/src/Multiselect.vue',
        // './node_modules/vue-tables-2/**/*',
        './node_modules/bootstrap-vue/src/components/**/*.js',
      ],
      defaultExtractor: (content) => {
        const contentWithoutStyleBlocks = content.replace(/<style[^]+?<\/style>/gi, '');
        return contentWithoutStyleBlocks.match(/[A-Za-z0-9-_/:]*[A-Za-z0-9-_/]+/g) || [];
      },
      whitelistPatterns: [
        /-(leave|enter|appear)(|-(to|from|active))$/,
        /^(?!cursor-move).+-move$/,
        /^router-link(|-exact)-active$/,
        // custom
        /^multiselect/,
      ],
    }) : '',
  ],
};

Any idea why this is happening and if there’s a way to get reasonable build times using the latest version?

Many thanks

[leeoniya]

i’d also be interested with how it improves here (tested against 1.4.0):

https://github.com/leeoniya/dropcss#performance https://github.com/leeoniya/dropcss/tree/master/test/bench#readme

the source & corpus for the stress bench are in the second link, if interested.

[Ffloriel]

I added a branch here. You will see a package named comparison. It will run PurgeCSS v1 and PurgeCSS v2 and print times in the console. Was thinking of going through the performance investigation too so I’ll definitely be open to review a PR about it. Thanks!