On TeX-enabled sites, pressing any character in the question/answer box re-renders all TeX equations. I have found this to be incredibly inconvenient. In posts with long answers, I have found that there is a significant delay between when I pressed a key and when the output is rendered. Typing becomes something of a pain due to this lag, especially when trying to accurately use the backspace key.
On slower computers, the lag grows worse rapidly. A workaround I frequently have to use is typing my entire post into Notepad/Gedit, pasting it over.
Would it be possible to reconfigure the preview script to only re-render MathJax if a character was changed in a MathJax equation?