It is amusing that, in my particular environment, KaTeX is slower than MathJax 3 in processing time but actually faster when font loading time is accounted for. Both loads from your domain so there should be no routing issue; KaTeX fonts turned out to be substantially smaller than MathJax 3 at least in this particular case. Is this intentional or just a lucky coincidence for KaTeX? (KaTeX is also ~70% smaller than MathJax 3 in their gzipped forms, so it might well be intentional!)