scss compile performance improvement

[sametsafak]

Hello,

I just figured out some performance issue with an scss function called luminance. I don't know what to do for solving or improving it but just wanted to inform.

I tried this with a fresh, empty coreui vue admin template. (@coreui/coreui-pro: 4.1.0)

Normally, when I edit anything in any scss file (like custom.scss), compile time is like 3000-5000 milliseconds.
But when I put a @return 1; in @coreui/coreui-pro/scss/_functions.scss:197 (luminance function's starting line) to prevent some calculations, It compiles 700 milliseconds.

Somehow, this function taking so much time and makings scss development a bit hard.

Edit: I tried to upgrade template with yarn upgrade command and now it takes even longer like 7000ms and somehow it compiles 2 times when i save anything. Maybe this can be another issue in v4.1.4.

Edit2: To learn which versions of packages users have, you can ask users to use this command while creating an issue:
npx envinfo --system --npmPackages '{coreui,@coreui/*}' --binaries --browsers
It can be a good touch :) here is my export:

  System:
    OS: macOS 12.2.1
    CPU: (10) x64 Apple M1 Max
    Memory: 6.56 GB / 64.00 GB
    Shell: 5.8 - /bin/zsh
  Binaries:
    Node: 14.18.2 - /usr/local/bin/node
    Yarn: 1.22.17 - /usr/local/bin/yarn
    npm: 6.14.15 - /usr/local/bin/npm
  Browsers:
    Chrome: 99.0.4844.51
    Safari: 15.3
  npmPackages:
    @coreui/chartjs: ^3.0.0 => 3.0.0 
    @coreui/coreui-pro: ^4.1.0 => 4.1.4 
    @coreui/icons: ^2.1.0 => 2.1.0 
    @coreui/icons-vue: ^2.0.0 => 2.0.0 
    @coreui/utils: ^1.3.1 => 1.3.1 
    @coreui/vue-chartjs: ^2.0.0 => 2.0.1 
    @coreui/vue-pro: ^4.1.0 => 4.1.4 

[mrholek]

The luminance function is necessary from the accessibility point of view. It calculates each color.

See https://www.w3.org/WAI/GL/wiki/Relative_luminance
See https://www.w3.org/TR/WCAG20-TECHS/G17.html#G17-tests