PHP Version Directly Affects WordPress Speed
WordPress is built on PHP, and the version of PHP your server runs determines how fast that code executes. Each major PHP release includes performance improvements to the language engine itself — the same WordPress code, the same plugins, the same theme, running measurably faster simply by upgrading PHP. Running an outdated version means your site is slower than it needs to be on every single page load.
How Much Faster Is Newer PHP
PHP performance has improved dramatically over the last several major versions. PHP 7.0 was roughly twice as fast as PHP 5.6. PHP 8.0 brought another 10–20% improvement over PHP 7.4 for typical WordPress workloads, and PHP 8.1–8.3 each added incremental gains through JIT (Just-In-Time) compilation improvements and internal optimizations.
In practical terms, a WordPress page that takes 400ms to generate on PHP 7.4 might take 300–350ms on PHP 8.2 — a reduction that applies to every uncached page load. For sites with heavy PHP processing like WooCommerce stores, the difference is more pronounced because there is more PHP code to execute.
Security Implications
PHP versions have a defined support lifecycle. Each version receives active support (bug fixes and security patches) for two years after release, then security-only fixes for one additional year. After that, the version is end-of-life (EOL) and receives no patches at all — including for security vulnerabilities. Running an EOL PHP version exposes your site to known, unpatched vulnerabilities.
As of early 2026, PHP 8.1 is in security-only support, PHP 8.2 and 8.3 are in active support, and PHP 8.4 is the latest release. Anything below PHP 8.1 is past end-of-life.
Why Sites Stay on Old Versions
The most common reason is plugin or theme compatibility. Some older plugins use deprecated PHP functions or rely on behaviors that changed in newer versions. Upgrading PHP can cause these plugins to throw warnings, errors, or break entirely. This creates a situation where site owners are stuck on old PHP because one or two plugins have not been updated.
The solution is not to stay on old PHP indefinitely — it is to identify the incompatible plugins (usually visible as PHP warnings or fatal errors after upgrading) and either update them, find alternatives, or contact their developers. Most actively maintained plugins support current PHP versions.
How to Check and Upgrade
You can check your PHP version in the WordPress admin under Tools > Site Health > Info > Server. Most managed hosting providers offer PHP version switching through their control panel — it is typically a dropdown selection that takes effect within minutes. Before switching, test on a staging environment if your host provides one.
The WordPress Site Health screen also flags outdated PHP versions and will recommend upgrading when you are behind.
Further Reading
- PHP Supported Versions (php.net) — Official PHP version support timeline showing active support and security-only dates for each release.