Following up on my recent performance report with essentially some conclusive results. Turns out that the reported issue is related more directly to the version of PHP than to the version of WordPress. So in other words, WordPress runs a bit faster on newer versions of PHP. As explained previously, after I upgraded my sites to WordPress 4.4, Googlebot reported slightly longer load times for my pages. The slower loading average was seen across numerous sites, and it looked like the WordPress 4.4 update was to blame.
So I posted about the issue with some screenshots and put it out there to get some feedback and insight as to what was happening. Who knows, perhaps others were experiencing (or not experiencing) similar performance issues. Fortunately, a short time later readers were chiming in with all sorts of useful feedback and ideas:
Its very well that you have one plugin or theme used on all the sites that runs slower with version 4.4.
Comment by Pace:
Do they all run jetpack? Connected to your WP.com account?
Comment by Kristian:
Checked 9 of my sites, if anything my times have gone down like 5%.
Just wondering if it’s some server configuration. Media Temple are pretty good though… PHP7?
Comment by Connie:
It seems that the reason for this is un outdated PHP-version, after updating PHP from 5.3.7 to 5.6.1 (if I remember right), the same installation got noticeable faster with PHP 5.6.1.
After ruling out some of these possibilities, it became clear that the performance decrease probably was due not to WordPress but rather to running an older version of PHP, version 5.4 (Media Temple’s default version). Soon thereafter I upgraded all sites to PHP 5.6 (the most recent version available running Plesk 12.0). After upgrading I waited about six weeks to give Googlebot plenty of time to collect more crawl data. Here are the results:
As you can see, upgrading to PHP 5.6 eliminated extra loading time required by WordPress 4.4, thereby restoring my sites’ performance to their previous optimized baselines. So if you compare a set of before/after screenshots:
Perishable Press running PHP 5.4 & WP 4.4
Perishable Press running PHP 5.6 & WP 4.4
..you’ll see that running PHP 5.4 and upgrading to WP 4.4 in December resulted in a performance decrease. Then later running WP 4.4 and upgrading to PHP 5.6 in March resulted in a performance increase, thereby restoring load times to their previously recorded amounts. And on some sites, loading times are even faster than they were before.
I’m guessing at this point that upgrading to PHP 7+ would result in an even greater performance boost, especially as WordPress continues making strides toward the latest techniques and functionality. So that brings us to the moral of this two-part story:
WordPress runs a bit faster on newer versions of PHP.
If you’re running WordPress 4.4 or better and care about things like performance, optimization, and SEO, it is highly recommended that you run at least PHP 5.6 to keep your site operating at maximum efficiency.
Next year, I’ll be working on upgrading to PHP 7 or whatever is available by then, but for now I am satisfied with the improved performance of PHP 5.6 running latest WordPress.
Thank you to everyone who shared feedback and ideas to help resolve this issue :)