PHP 7 is a clear win compared to earlier versions of PHP, yet, unlike Nexcess, many WordPress hosts haven’t upgraded. It’s difficult to get a clear view of the exact adoption rates of PHP 7, but according to figures from Jordi Boggiano, developer of Composer, PHP 7 adoption rates are hovering around 20 percent, with nearly 40 percent of PHP sites based on PHP 5.6, 30 percent on PHP 5.5, and, worryingly, a substantial number based on even older versions.
WordPress accounts for about a quarter of all sites on the web, far more than any other PHP-based content management system or web framework. Many of the PHP 5.6 and older deployments are hosting WordPress sites.
PHP 7 offers numerous benefits compared to older versions of PHP. It’s faster, it introduces new features, and by the end of this year, it’ll be only actively developed version. There are a few reasons the vast majority of WordPress users are stuck on older versions, and most of them have to do with shared hosting companies not doing their job properly.
The speed benefits PHP 7 brings are not negligible. We should always take benchmarks with a pinch of salt, but testing has shown a 2-3 times performance increase for a WordPress site based on PHP 7 compared to one based on WordPress 5.6. That doesn’t mean your WordPress site’s pages will load three times faster, server-side processing is only one part of getting a web page loaded in a browser, but it’s a big part.
WordPress has occasionally been criticized as intrinsically slow, but that’s never been the case for a properly configured WordPress installation, especially when compared to the other benefits it brings. WordPress was limited by the performance of the underlying PHP engine, but with the release of PHP7, many of the historic problems with PHP were solved.
The web is always slow to change. The vast majority of WordPress sites use low-cost shared hosting, and many hosting providers don’t have the right incentives to upgrade their platform. Even though PHP 7 is more-or-less a drop-in replacement for earlier versions, there’s some work to be done, and the majority of shared hosting providers simply haven’t made the effort, in spite of the obvious advantages to their users.
PHP version 5.5 support ended last July, which means it’s no longer under active development, and, even worse, it’s no longer getting security updates. Any vulnerabilities in that version of PHP will not be fixed. PHP 5.6 will be actively supported until the end of this year, and will receive security updates for another a couple of years, but given the obvious benefits of upgrading, why are WordPress hosting providers holding back?