>>8
PHP is very slow. Most CL implementations compile to native code which tends to be ~2-3 times as slow as the C equivalent (unless you start microoptimizing and adding declarations left and right). The only reason I could imagine someone wanting to compile Lisp to PHP is because PHP is on every cheap hosting and they don't want to write PHP, but they have no alternative but to use it, thus compile *insert favorite language* to PHP.