The RapidXml library is pretty similar to AsmXml, except that it's written in C++. Browsing around the "Links" section on the AsmXml website, I came across a site that performs speed comparisons between the various parsers out there. RapidXml does appear to come pretty close to AsmXml in terms of speed.
Source: http://xmlbench.sourceforge.net/results/benchmark200910/inde...