Recent versions of PHP provided huge real world performance gains. The constant focus on improving PHP performance has really produced startling results. Starting with PHP 7.0 every major release of PHP has been noticeably faster than the last and the focus on performance is still core to the objectives of the PHP developers with the recent v8.0 release using just in time compilation techniques.
So how does this alter my google ranking you may be asking. Quite simply because Google and other search engines take page render time into account as an indexing factor when they crawl your websites.
These search engines know a lot more about your website's performance than you might think. Just try using the Google developers Page Speed Insights tool to see all the detailed information that is returned about exactly how your page is constructed, where the bottlenecks are etc.
Now some of the points reported in speed analysis tests such as Google Page Speed Insights are related to unoptimized code and delivery issues that could be improved upon. However many of the factors relating to speed such as 'First Contentful Paint' and 'initial server response time' are all related to how quickly your web server can process and return a page.
This is where the performance of PHP for any PHP hosted pages comes into play, and so naturally running the latest versions of PHP gives an advantage in this regard.
If you are not sure what version of PHP your web server is currently running read our guide on checking your PHP version. If you know your PHP version but are not sure about how to upgrade it, read our PHP upgrade guide.