Ever since I had heard about PHP 7 being released I have been looking forward to the time when it would be an option on WP Engine.
WP Engine is our most used managed hosting service for many reasons, but it has been running on PHP 5.5 for a while now and wordpress itself along with plugins like woocommerce currently recommend at least PHP 5.6.
Clearly it was time for an upgrade! WP Engine had made the decision to skip upgrades to PHP 5.6 because of minimal performance gains and a very limited time planned to support it.
They planned ahead to go straight to 7, so we've been waiting extra long for this.
In mid 2016, I was asking WP Engine support when it would be available and they were unable to give a definitive date and were unwilling to even give a time range.
To my surprise just this past December of 2016, I asked support about it again and low and behold, they now had it available. Why it was not a widely known fact, I don't know, but I'm glad I asked again!
PHP 7 Benefits
So what's so great about PHP 7?
Well, it's better at the most important thing that people need on a site of course.
SPEED
It's just plain old faster.
An upgrade to PHP 7 is a straight up free speed boost. PHP 7 can handle uncached hits 2-3x faster than PHP 5.5 (2).
The first site I tried an upgrade on, knocked a half second off of the load time and I did nothing except upgrade.
Free speed is so nice. In addition to speed, it brings 30-50% improvements in memory consumption, and can serve up to 3x as many requests per second and handle more traffic with the same number of resources (2).
WP Engine ran some tests of it's own and found the claims to be true with benefits from 2.6x to 6.6x better performance than PHP 5.5 (1).
What You Need to Know
So what's the catch?
Well, PHP 7 does have some changes in the code and some different/changed/removed functions in it, so some Wordpress plugins and themes currently out there will not work with PHP 7.
This means an upgrade could just break some of your site functionality.
WP Engine made a plugin just for this reason. The "PHP Compatibility Checker" plugin was made by WPEngine to scan your plugins and themes and identify any errors or warnings that may be caused by an upgrade.
It breaks it down item by item so you can see where the trouble is and will let you know what the offending function is. For these instances, I would generally let the plugin/theme author know that it is out-of-date for the latest php version and wait for them to update before switching to PHP 7.
WP Engine support made it very clear to me that they want everyone to make sure that there will be no issues once switched because it can be a royal pain to switch the site back to PHP 5.5.
The actual upgrading is done by the WP Engine staff, so to initiate a switch just contact the WP Engine support team and they will open a ticket.
You can have it done as soon as possible, or you can schedule it to be upgraded during a lower traffic time or whenever else you may choose. Upgrades can be done on an install by install basis, so you can upgrade some of your installs even if others are incompatible.
Here is a suggestion for WP Engine users who are nervous about upgrading even after running the compatibility checker. Duplicate your install and upgrade the duplicate to PHP 7, then test your brains out to double-check that everything will be ok. Then when you are done, just delete the test install. Safe testing while your live site stays untouched!
Your Next Steps
The bottom line is, PHP 7 is ready for WPEngine.
Make sure your install core wordpress version and plugins are up-to-date.
Check compatibility with the PHP Compatibility Checker.
Double check your install by duplicating it and testing the upgrade on the duplicate if desired.
Upgrade if everything checks out and reap the benefits of free speed.
If your hosting provider doesn't yet offer PHP 7, then you might be on a bad hosting service and you should look to upgrade to WPEngine or Kinsta. Once you have made the move to PHP 7, then it's time to look into more ways to speed up your wordpress site.