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How to choose the right PHP version for performance

Maxim Tsitsejev
Updated

Applies to: All plans

Before you start: You need access to cPanel for your service (open it by single sign-on from client area -> Services -> My Services, then Log in to cPanel). It also helps to know which app each website runs (for example WordPress) so you can check it after switching.

Running a modern PHP version is one of the easiest ways to make your site faster. Each major PHP release runs your code more efficiently and uses less memory, so a site on PHP 8.x typically handles more visitors within your plan's CloudLinux limits than the same site on an older release like PHP 7.x. Newer versions also receive security fixes, while older ones eventually stop being supported.

This article explains why a newer PHP is faster, how to check your site is compatible, and how to switch versions safely in cPanel.

Why a newer PHP version is faster

  • It executes your code more efficiently. Modern PHP does the same work with fewer CPU cycles, which matters because each account has a CPU/SPEED limit under CloudLinux.
  • It uses less memory per request. That leaves more headroom against your plan's physical memory (PMEM) limit, so you are less likely to hit a 508 "Resource Limit Reached" error under load.
  • It stays supported. Newer versions keep getting security and bug fixes; very old versions do not.

On our platform PHP also runs behind LiteSpeed, and pairing a modern PHP with caching gives the best results. See How LiteSpeed and LSCache make your site fast.

Check your site is compatible first

Jumping straight to the newest PHP can break a site that uses older code. Reduce the risk before you switch:

  1. Update your software. For WordPress, update core, your theme, and all plugins to their latest versions. Older code is the most common cause of problems on a newer PHP.
  2. Check the requirements. Confirm your CMS, theme, and plugins state support for the PHP version you want.
  3. Test on a copy, not live. Where possible, try the new version on a staging copy of your site so visitors are never affected. See How to create a staging copy of your site.

If you would rather not do this yourself, Managed plans include managed updates and free migration assistance, and you can ask our team to handle the change.

Switch your PHP version in MultiPHP Manager

PHP is set per-domain, so you can run different versions for different sites in the same account.

  1. In cPanel, go to cPanel -> Software -> MultiPHP Manager.
  2. In the domain list, tick the box next to the domain (or domains) you want to change.
  3. Open the PHP Version dropdown (top right) and choose your target version, for example a current PHP 8.x release.
  4. Select Apply.

Result: The chosen domain now shows the new PHP version. Open your website in a fresh browser tab and click through the main pages to confirm everything still works.

If you need specific PHP modules afterwards, enable them under the tool labelled Select PHP Version (the PHP extensions selector). See How to enable or disable PHP extensions.

Troubleshooting this task

  • A page shows a 500 error or blank screen after switching. The site likely uses code that is too old for the new version. Switch the domain back to the previous PHP version in MultiPHP Manager, update your plugins and theme, then try again. For WordPress, see Fixing the WordPress white screen of death.
  • A feature stopped working. A required PHP extension may not be enabled on the new version. Check the Select PHP Version extensions list.
  • The version you want is not listed. We provide a range of supported versions; pick the closest current release. If you need one that is not offered, contact support.
  • The site is still slow after upgrading. PHP version is only part of the picture. Enable caching with How to speed up WordPress with LiteSpeed Cache and review Why is my website slow?.

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