Installing the Figure numbering extension slows down all page rendering a lot

From Michael Hamann:

I think there are two things to do: a) find out why the CSS is so slow to generate. It shouldn't be that slow. b) enable caching as regardless how fast the CSS is, we shouldn't have any non-cached CSS. Instead, we should find some fast-to-compute parameters like the current language and the last change date of the configuration to add to the URL.