Please download and try out the latest beta release of pyparsing. It includes support for user-defined regular expressions (using the Regex class), and re-implements several classes internally as regular expressions. My testing shows a 30-40% speed improvement with this version. While this passed all of my unit and regression tests, I am concerned that I may have some forward compatibility issues.
Please report your experiences (good and bad) in upgrading to version 1.4. BUT be sure to retain your old version of pyparsing, as I expect to have to make at least *some* changes before the final 1.4 release.