regex performance

I'm doing some performance comparisons between Rogue Wave's Regexp class (http://www.roguewave.com/support/docs/tlsref/rwcregexp.cfm) and boost::regex using simple expressions like "^metal.*" and "[0-9]+" with regex_search(). regex is slower by a factor of 6, measuring cpu time (on a SunBlade 100 runing Solaris 8). Is there anything I can do to speed it up? I tried using different values of boost::regbase::flag_type_ to adjust how the regular expressions are interpreted, but with little effect. Any other ideas? (I'm using boost_1_27_0.) Thanks, -- Paul M. Dubuc