Hi, after doing analysis on my forum with PageSpeed Insights, I see that discourse use ~55 kB of unused css.
In my opinion this is a much, so you can use PurgeCSS to optimize discourse styles.
I think this is an important feature, that will improve website load time
The report is not optimized for Discourse which is a long living single page app.
We can not remove all the CSS for the badges page, cause the badges pages will be unstyled. We do not have the architecture to ship the CSS for the badges page just when you visit it. We will consider long term changes here but there is no easy win.