I recently typed an answer with a few formulas in it. While I was typing, my browser constantly reloaded the preview part below the typing window. Because MathJax apparently does three passes over the text, typing became so slow that I could not even read the source code I was typing without some waiting.
Of course, I could just write in some editor, then copy into MO. But switching the MathJax preview off temporarily would be a somewhat nicer option. Is that possible?
The comments on this related question suggest that there are more or less complicated workarounds (I followed the links and could not make anything out of them). If we cannot have a "preview off" button, then maybe we could at least have an entry in the help center that explains how to switch MathJax on and off in the browser?