PHP NG (called PHP 5.7 if you like) is still in the alpha development stage, but it has already shown amazing performance improvements. The key is to still maintain compatibility with PHP 5.6.
Dmitry Stogov has more and more ideas for improving PHP speed after the first release in mid-January this year and the milestone update in early May. Special contributors are from Xinchen Hui @雪migratory bird, Nikita Popov, etc.).
By mid-July, these efforts finally bore fruit. Tests showed that the performance of the version under development was nearly doubled compared to PHP 5.6. Testing was conducted on rendering a WordPress 3.6 front-end page.
For the same page, PHP 5.6 takes 26.756 seconds to render 1000 times, while PHP NG takes 14.810 seconds. It's not over yet, you can learn more about the goals and notes at http://wiki.php.net/phpng.
The secret to this performance improvement is that nearly 60% of CPU instructions were replaced with more efficient code. PHP 5.6 requires 9,413,106,833 CPU instructions to perform 100 renders, while PHP NG requires only 3,627,440,773 instructions.
Because most extensions support PHP NG, you can easily build your own environment for testing. PHP NG is not expected to release a stable version this year due to the large amount of planning, and hopefully a stable Beta or even RC version will be released in 2015.