Install Katex for moodle Math rendering
Speed is not everything. MathJax has some features that KaTeX does not. In particular it is more accessible. The speed test page above exaggerates the speed difference. On more practical pages the difference is not as noticeable.
However, If you are interested in trying KaTeX in Moodle 2.8+, you can use the following procedure. Go to Site administration -> Appearance -> Additional HTML. In the box Within HEAD put
In Before BODY is closed include
Then enable the TeX notation filter and disable MathJax filter. TeX expressions will be filtered and displayed as images first by the TeX notation filter. KaTeX will then replace the images with its display.
I have tried to insert your code within the head and before the BODY is closed in the Additional HTML section. It gives 'This page is not working' and 'Chrome detected unusual code on this page and blocked it to protect your personal information (for example, passwords, phone numbers, and credit cards).'
I am using Moodle 3.4 on a current version of Chrome.
Is there something new in Moodle that scrubs out scripts in the Additional HTML?
I just ran it with the development master, and it seems to be working for me. Make sure that MathJax filter is off. Normally the additional HTML is not scrubbed. Are you using one of the standard themes or a custom one? That might interfere.