They may not know it, but Facebook users are navigating the ultra-popular social network with a new and improved computing infrastructure. Company officials announced Dec. 9 that it is again revamping the way it handles PHP-based Web pages, to improve the experience for its 800 million users.

Last year, Facebook deployed HipHop for PHP to help support the growing number of Facebook users.

“While HipHop has helped us make significant gains in the performance of our code, its reliance on static compilation makes optimizing our code time consuming. We were also compelled to develop a separate HipHop interpreter (hphpi) that requires a lot of effort to maintain. So, early last year, we put together a small team to experiment with dynamic translation of PHP code into native machine code,” explained Jason Evans, a software engineer on the HipHop team at Facebook, one of nearly 20 people who have contributed to the hhvm project so far.

According to Evans, the upshot of all that work is a new PHP execution engine based on the HipHop language runtime called the HipHop Virtual Machine (hhvm).

“We’re excited to report that Facebook is now using hhvm as a faster replacement for hphpi, with plans to eventually use hhvm for all PHP execution,” Evans wrote in a Facebook Note.

According to Facebook, this PHP execution engine is 60 percent faster than its current PHP interpreter and uses 90 percent less memory.

“The difference between eight-second and five-second reloads due to switching from hphpi to the hhvm interpreter makes a big difference to productivity, and this improvement will be even more dramatic once we enable the translator,” Evans said.

Originally, PHP was designed as a Web scripting language to add dynamic content to Web pages. “PHP is a vital part of Facebook, in that it, along with JavaScript, is used to help assemble each user’s unique home page,” ComputerWorld explained.

“As with code rendered by most scripting languages, however, PHP applications do not run as fast as programs written in full-fledged programming languages such as C++, which are compiled into machine-readable byte code ahead of time,” the report said.

Ultimately, Facebook’s HipHop transforms PHP extensions into highly optimized C++ code, which means they run faster when executed.