My apologies if this should be a comment rather than answer, but [robjohn](https://math.stackexchange.com/users/13854/robjohn)  has a [website](http://www.math.ucla.edu/~robjohn/math/mathjax.html) with some very handy bookmarks to deal with these issues. Obviously it would be preferable if a bookmark bar were not needed, but `rendering on` and `rendering off` are quite helpful currently.