There have been a lot of complaints and bug reports about the state of the $ MathJax $ editing experience all around SE lately. We've heard you, and with a lot of help from the kind folks from $ MathJax $ (a special shout out goes to Davide), things are finally moving along.

Today we're rolling out a beta version of the $ MathJax $, PageDown and Markdown integration on meta.math.SE and math.SE, that addresses a bunch of issues. We chose math.SE, because it already proved to be helpful with $ MathJax $ issues in the past (it is the only site that runs on the latest beta.mathjax.org bits).

So please be extra mindful of any $ MathJax $ issues you may encounter in the following days, and please report any bugs here on meta.math.SE.

$P.S.$ Don't forget to disable the editing preview userscripts

$P.S. 2$ Here's a short list of fixes, provided by Davide:

• disabled the fast preview during editing
• disabled the assistive MathML during editing
• processSectionDelay = 0 during editing reduces the flickering and speeds up refreshes slightly
• disabling the noErrors extension during editing, so that actual error messages appear
• allow the editor to interrupt MathJax
• add support for CommonHMTL for the best results
• reset the \label{} data before each typeset to prevent multiple-defined label errors

Update

The changes from this beta graduated network-wide in build rev 2016.4.25.3507