No idea why it's crazy slow in production and fast locally, nevertheless, is_svg in the SVG engine is horribly slow and it runs for every file.

We could start by making that check only run for files with the .svg extension and see if there's a more efficient technique than using BeautifulSoup. As far as I remember BS4 looks for a fully correct SVG, when we're probably more interested in a quick check to see if we're going to try to convert the content with rsvg or not.