I'm talking about TTFB, not complete page load. (Which is also what I stated in my first post in case you didn't see that.)
http://www.webpagetest.org/result/151208_TR_1KFJ/
Keep in mind that PHP only affects the TTFB. As you can see, it matches the results I posted in my first post.
The forum itself uses quite some images and other third party resources so it's not the fastest when it comes to the complete page load.