Checkout this link -
http://65.1.136.127/developerlife/parsertest2/performance.html It has some benchmarking statistics for various popular parsers. A
word of caution though, this data is quite old and there are newer versions of these parsers available today. Not to mention there are more number of parsers available today that are not in the list. So take the data with a pinch of salt
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Ajith Kallambella M. Sun Certified Programmer for the Java�2 Platform.
IBM Certified Developer - XML and Related Technologies, V1.