The premise is only mostly true. See: How to make LISP go faster than C, http://docs.google.com/gview?a=v&q=cache:pJg0zHyA8s8J:www.lrde.epita.fr/~didier/resear

The premise is only mostly true. See: How to make LISP go faster than C, http://docs.google.com/gview?a=v&q=cache:pJg0zHyA8s8J:www.lrde.epita.fr/~didier/research/verna.06.imecs.pdf+lisp+faster+than+c&hl=en&gl=us&sig=AFQjCNHLVC-I-RoHNFuPCOemUhyUYfrpHg http://docs.google.com/gview?a=v&q=cache:pJg0zHyA8s8J:ww... As an example, consider C pointers. The compiler never knows if two objects passed by reference are going to overlap in memory, so it can't do certain optimizations that seem obvious to a human that "knows" the pointers won't overlap.