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

99% of the running time for serving the style sheet is spent in less compilation. This is because caching is disabled as the content can change dynamically when the configuration of either the defined figure counters or the defined figure types changes - or when the localization, e.g., for the figure type name changes (not the language, but the actual string). The solution is to enable caching and to compute and append a hash of everything that influences the CSS to the URL to avoid false caching.