Update:
I have done some new benchmarks of WordPress with a page caching plugin. This time HPHP gave even more impressive results.
With a page caching plugin, HPHPed WordPress has gained 2.7x speedup
over PHP. Dynamic page generation of HPHP is super fast that its speed
is more than a quarter of static content by Nginx.
Please read more details from
http://huichen.org/en/2010/06/wordpress-3-benchmark-part-2/--
Hui Chen
Graduate Research Assistant
Microelectronics Research Center
The University of Texas at Austin