unladen-swallow does not get a 5x speedup, but pypy gets pretty close.<p><a href="http://morepypy.blogspot.com/search?updated-min=2010-01-01T00%3A00%3A00%2B01%3A00&#38;updated-max=2011-01-01T00%3A00%3A00%2B01%3A00&#38;max-results=1" rel="nofollow">http://morepypy.blogspot.com/search?updated-min=2010-01-01T0...</a><p><a href="http://article.gmane.org/gmane.comp.lang.lua.general/42210" rel="nofollow">http://article.gmane.org/gmane.comp.lang.lua.general/42210</a> is tangentially related.