XPath and performance

I'm looking for a simplifed XPath-like language, one that is more performance-
concious than full XPath (e.g., would be implementable with SAX or preferably, 
a pull parser).

So far, I've found Sequential XPath [1], but was wondering if there was 
anything else out there.

Cheers,

[1] http://www.idealliance.org/papers/xml2001papers/slides/Desai/Introduction 
20to%20SXPath.ppt

--
Mark Nottingham, Research Scientist
Akamai Technologies (San Mateo, CA USA)