The Kinsta.com blog has a new post with the results of some benchmarking they've done around WordPress comparing PHP 5.5, PHP 5.6 (PHPNG) and HHVM in response time (well, time taken for the request).

If you remember we wrote an article a good couple of months ago when WordPress 3.9 came out that HHVM was fully supported beginning with that release, and we were all happy about it. The initial benchmark results showed HHVM to be far more superior than the Zend engine that’s currently powering all PHP builds.

[...] Obviously you have to compromise based on your (or rather your sites’) needs but is it worth it? How much of a performance gain can you expect by switching to HHVM? [...] Today I finally took the time to set up a test environment and do some tests to compare a couple of different builds with a fresh out of the box WordPress install and one that has a bunch of content added plus runs WooCommerce!

The testing was all done locally on virtual machines (using Vagrant setups) and two different kinds of test WordPress installations. They share the results in the post, showing the differences between the HHVM installations and the plain PHP ones. The results also show the differences between having the opcode cache on and off. Curious to see how it would perform outside of a local system, they also pushed the same configurations out to a DigitalOcean instance with some slightly different results.