The work in 4.5 on O(1) template instantiation lookup time is already showing benefits: http://article.gmane.org/gmane.comp.lib.boost.devel/194545 http://article.gmane.org/gmane.comp.lib.boost.devel/194538 http://www.boostpro.com/vault/index.php?&directory=variadic_templates in tuple.benchmark.zip Thanks very much for this work! -regards, Larry