[ShadyCSS] App loading performance issue in Chrome <= 45

[vadzimdubina]

Description

We started using WebComponents in our apps and for apps built with Chromium <= 45 we experienced app loading performance issue. Application loading time increased from 2-5 seconds to 2-5 minutes. With Chrome performance tool we found that this regex takes a lot of time:

polyfills/packages/shadycss/src/css-parse.js

Line 257 in 78c69a5

varApply: /[^;:]*?:[^;]*?var\([^;]*\)(?:[;\n]|$)?/gim,

Is there any reason why we can't simplify css-property selector from [^;:]*? to [\w\s\d-]*?? It increases performance even in up-to-date browsers: https://jsbench.me/dsk62aojjg/1

Browsers Affected

• Chrome
• Firefox
• Edge
• Safari
• IE 11

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[stale]

This issue has been automatically closed after being marked stale. If you're still facing this problem with the above solution, please comment and we'll reopen!