Here at WP Engine we’ve been looking at ways to bring the speed of our HHVM based Mercury platform to even more of our customers. Fortunately, the PHP team has spent the past year (or so) in a speed war with Facebook’s HHVM team.

According to tests by each respective team, HHVM and PHP 7 have been neck and neck when it comes to the number of raw, uncached hits they’re able to handle. We’re seeing some really impressive numbers out of PHP 7, however.

Now, while I don’t have anything to announce as far as PHP 7 availability goes — it hasn’t even been officially released yet — you can bet that we’re working hard to bring a stable, performant implementation to our customers.

To wet your whistle, let’s take a look at the raw data from a siege test — 25 concurrent users over 5 minutes across 10 randomly selected URLs — run against a basic WordPress (4.3.1) install on our Mercury Vagrant

PHP 5.5

Transactions:              4354 hits
Availability:              100.00 %
Elapsed time:              299.64 secs
Data transferred:          17.23 MB
Response time:             1.21 secs
Transaction rate:          14.53 trans/sec
Throughput:                0.06 MB/sec
Concurrency:               17.59
Successful transactions:   4354
Failed transactions:       0
Longest transaction:       2.04
Shortest transaction:      0.12

HHVM

Transactions:              5256 hits
Availability:              100.00 %
Elapsed time:              299.53 secs
Data transferred:          20.06 MB
Response time:             0.92 secs
Transaction rate:          17.55 trans/sec
Throughput:                0.07 MB/sec
Concurrency:               16.12
Successful transactions:   5256
Failed transactions:       0
Longest transaction:       11.54
Shortest transaction:      0.43

PHP 7

Transactions:              11333 hits
Availability:              100.00 %
Elapsed time:              299.38 secs
Data transferred:          44.84 MB
Response time:             0.16 secs
Transaction rate:          37.85 trans/sec
Throughput:                0.15 MB/sec
Concurrency:               6.16
Successful transactions:   11333
Failed transactions:       0
Longest transaction:       0.77
Shortest transaction:      0.02

This install was populated with dummy data from WP Test, used Twenty Fifteen for its theme and had Yoast SEO, Contact Form 7, and WordPress Importer active.

php7-graph1

As you can see, the number of raw hits that could be handled under HHVM (1.2x faster) was one-upped by the PHP 7 (2.6x faster) implementation. It gets even more exciting when you look at a similar test — 25 concurrent users, 5 minutes, 10 randomly selected URLs — for bbPress…

WordPress (4.3.1) + bbPress (2.5.8)

PHP 5.5

Transactions:              680 hits
Availability:              100.00 %
Elapsed time:              299.29 secs
Data transferred:          3.54 MB
Response time:             10.29 secs
Transaction rate:          2.27 trans/sec
Throughput:                0.01 MB/sec
Concurrency:               23.39
Successful transactions:   680
Failed transactions:       0
Longest transaction:       12.39
Shortest transaction:      1.51

HHVM

Transactions:              3194 hits
Availability:              100.00 %
Elapsed time:              299.41 secs
Data transferred:          12.55 MB
Response time:             1.84 secs
Transaction rate:          10.67 trans/sec
Throughput:                0.04 MB/sec
Concurrency:               19.67
Successful transactions:   3194
Failed transactions:       0
Longest transaction:       15.37
Shortest transaction:      1.12

PHP 7

Transactions:              4521 hits
Availability:              100.00 %
Elapsed time:              299.28 secs
Data transferred:          23.52 MB
Response time:             1.15 secs
Transaction rate:          15.11 trans/sec
Throughput:                0.08 MB/sec
Concurrency:               17.38
Successful transactions:   4521
Failed transactions:       0
Longest transaction:       2.21
Shortest transaction:      0.60

This install was populated with dummy data from EpicWebs bbPress Test Data, used Twenty Fifteen for its theme and had Yoast SEO active.

php7-graph2

While HHVM (4.7x faster) presents a fairly significant bump in the number of raw hits it can handle, PHP 7 (6.6x faster) still edges it out in pure performance. This means once we’re ready to make PHP 7 widely available, most customers will see serious performance gains without having to do much more than make sure their plugins, themes, and core install are up to date.

I’m sure if you’ve read this far, you’re probably pretty interested in playing with PHP 7. If so, consider downloading the Mercury Vagrant and testing your current site against the PHP 7 implementation we’ve provided there.

Should installing a Vagrant and testing something on HGV be outside of your comfort zone, I shared some HGV setup and quickstart tips in a presentation I gave at WordCamp Sacramento earlier this month. Feel free to go over my slides if you’d like!

Happy testing!


Jason CosperJason Cosper works as the Developer Advocate for WP Engine. He loves digging into interesting problems and learning new things. Currently, he spends most of his days getting elbows deep in huge messes and doling out WordPress optimization advice. In his spare time, Cosper enjoys spending time with his wife and very tiny dog, grilling meats, sampling assorted whiskeys, writing cranky tweets about the Lakers and brewing coffee.