Today, almost every site is not running on ancient HTML, but on the complex CMS, written in PHP. Most often it can be Joomla, WordPress, Drupal and so on. Since such CMS are quite “heavy” (and, frankly speaking, not very efficient because of the large number of ‘extra’ components) systems – sooner or later any site administrator is faced with the problem of lack of resources in hosting.
Many webmasters in this panic (myself experienced it more than once), trying to get wise to components, debug the cache, and so on. All this is fine, of course, but there is a much simpler way.
Just upgrade to the latest version of PHP. This is usually done with a couple of clicks in the web-hosting control panel.
The difference in performance and speed of the site on any CMS before and after – will be different at times. The only thing is to check compatibility of your CMS and its modules, components, etc. with PHP 7.x before the upgrade; and don’t forget to make a backup.
In general, the transition to a new version of software – a great way to save on hosting. Someone can move to a VDS on a cheap virtual machine thanks to this 😉