[ck2]

Why not read the wiki and notice how Dmitry is trying different ideas for performance improvements? It started with memory optimizations but there are now many other little things like JIT regex.

It is all listed in the wiki and other ideas not attempted yet that might make it even faster.

Obviously not all code is going to be twice as fast, it is an average in a large program like wordpress. Some things more than twice as fast, some not so much.