That makes no sense whatsoever. Symfony2 is fast as hell. If you don't think so, you simply don't know how to properly configure it for production. There isn't much real speed you can gain from using weird things like Phalcon, unless you don't know the first thing about caching. In fact, not having all the caching mechanisms that Symfony2 gives you will probably slow down your application, even if your code is written in C.