Konkat theme's color-mix causing huge admin rendering slowdown - please consider caching it in a css variable.

[adrianbj]

Hi @ryancramerdesign - this commit processwire/processwire@a817943 is causing a huge slowdown when editing certain pages on my site. Everything is fine with the original Uikit theme, but when I switch to "default" the page doesn't finish rendering for about 15 seconds.

Note that to see the issue you need a page with a lot of elements - in my case the template has a lot of checkboxes fields, a table field, and is generally a behemoth - and you also need Tracy enabled. At first I thought Tracy itself must have started causing issues, but even with all panels disabled, it was having the same effect. If you disable Tracy completely, there is still a slight slowdown, just not anywhere near as noticeable.

Anyway, any chance color-mix could be removed? The other possibility that I have read about is to make sure that the color-mix value is cached in a css variable so it only needs to be calculated once. I haven't tested, but this might suffice.