This is the opposite question of this one. My purpose is that there is no need when you write only PHP5 code to have PHP4 compatibility. It is not helpful at all and due to differences between object models in those two version, it must be penalizing on interpreter performances (or am I wrong ?).

So my questions are :

• is it possible to recompile PHP5 without retrocompatibility with PHP4 or to disable it in any other way to gain performances ?
• if it is not possible, is there a project somewhere which aim that goal ?