SAX is popular with Java programmers because it is a powerful API. However, SAX programming involves writing a fair amount of low-level state tracking code. The open source HC toolkit enhances SAX with XPath support.
To remain as efficient as possible, HC is designed as a small layer on top of SAX. The version of HC available at the time of writing (0.4) is not yet optimized for speed, but it already performs adequately for most common programming projects. Be sure to visit http://www.ananas.org/hc for news on new features.