php is known much slower than static content. in a shared host, when a php request comes in, typically the web server need start up a php process and execute it.
regarding php lsapi, in fact it's fastest fast-cgi for php as of we know.
we've heard of "nginx + php-fpm" is fastest, our simple benchmark shows lsphp outperform it without doubt.
have you tested with just a "hello world" php page and same result ?