I regularly take notes in my advanced undergraduate math classes using LaTeX. The key is to (a) use macros --- make them up on the fly and just start using them. e.g. \pd{f}{g} for \frac{\partial f}{\partial g}, for instance, or \cF for \mathcal{F}, or \sHom for \operatorname{sHom}... (b) don't compile --- compiling during class will just confuse you. Make sure you've got enough info in the .tex file for you to understand what the notes are, and then fix typos and errors afterward. To tie back to (a), actually write the definitions for your new set of macros after class. (c) use Emacs --- if you're doing a lot of TeX you'll be happier with emacs and auctex. (d) type faster. If you can't go fast enough (or the lecturer is whipping through the blackboard faster than you can type), go back to paper & pencil. It's not that bad.