Yes, you can comment out several lines at once by selecting them and pressing Ctrl-/ (slash) (command-/ on a Mac). You can also use the comment package to comment out large sections of text. Just add
\usepackage{comment} </pre> <p>to your preamble, and then use</p> <pre> \begin{comment} ... \end{comment}
in the text to create a block comment.
Another option is to enable vi editor mode and use the standard vi commands for commenting.