PHP and WordPress: why updating the PHP version is crucial

Category: Performance | Reading time: 11 min

PHP is the programming language on which WordPress is built. Every page you visit, every article you publish, every plugin you use — everything is executed in PHP. Yet approximately 30% of WordPress sites still run on outdated versions of PHP. This is a major problem that affects both the performance and security of your site.

In this article, we explain why updating your PHP version is essential, what the concrete benefits are, and how to proceed safely.

Understanding PHP and WordPress

PHP is a server-side scripting language. Unlike HTML and CSS which are sent as-is to the browser, PHP is executed by the server before being sent to the visitor. This is what allows WordPress to generate dynamic content: posts, pages, comments, search results, etc.

Each major new version of PHP brings significant improvements:

• Execution speed: code is compiled and executed faster
• Memory management: better use of server resources
• Modern functions: new capabilities for developers
• Bug fixes: fixes for known issues
• Security patches: protection against vulnerabilities

WordPress officially recommends using PHP version 7.4 or higher, but the ideal is to use the latest stable version (currently PHP 8.2). Understanding why this matters can save you from performance issues, security breaches, and compatibility problems down the road.

The WordPress ecosystem and PHP

WordPress powers over 40% of all websites on the internet. This massive market share makes it a prime target for attackers, and PHP version management becomes a critical aspect of site security. Every month, new vulnerabilities are discovered and patched in newer PHP versions — if you're running an old version, those patches never reach your site.

Impact on performance

The impact of the PHP version on WordPress performance is substantial. Each major version brings significant performance gains.

The numbers that matter

Concretely, a site that takes 3 seconds to load on PHP 7.4 could take only 2 seconds on PHP 8.2. This is a difference perceptible by your visitors and favored by search engines.

Why PHP is faster

• JIT (Just-In-Time) compilation: introduced in PHP 8.0, it compiles code in memory for faster execution
• Internal optimizations: each version optimizes data structures and algorithms
• Better memory management: fewer resources consumed for the same result
• Improved OPcache: the compiled code cache is more efficient

Impact on security

This is perhaps the most important argument for updating PHP. Outdated PHP versions no longer receive security updates.

The PHP support timeline

• PHP 7.4: support ended November 2022 — no more security updates
• PHP 8.0: support ended November 2023 — no more security updates
• PHP 8.1: active support until December 2025
• PHP 8.2: active support until December 2026

A site running on PHP 7.4 or earlier is vulnerable to attacks that exploit flaws identified and fixed in newer versions.

Concrete risks

• SQL injection: unauthorized access to your database
• Remote code execution: takeover of your server
• XSS (Cross-Site Scripting): injection of malicious code into your pages
• Data leaks: theft of sensitive information

"Using an outdated PHP version is leaving the door open to attacks. Updating is the first line of defense for your WordPress site."

Compatibility and features

Beyond performance and security, updating PHP is essential for compatibility.

Impact on plugins and themes

• Developers are dropping support for older versions: new plugins and themes require PHP 8.0+
• Deprecated functions: some PHP functions are removed in newer versions
• Security updates: plugins won't fix vulnerabilities related to old PHP versions

WordPress itself

WordPress evolves with PHP. Recent versions of WordPress use modern PHP features that aren't available in older versions. Staying on an old PHP version also limits the features available on your site.

PHP versions: current state

Here's a summary of the current state of PHP versions:

Performance comparison between versions

To illustrate the concrete impact of updating, here are the results of real benchmarks on typical WordPress configurations:

Standard WordPress benchmark

• PHP 7.4: 100 requests/second
• PHP 8.0: 118 requests/second (+18%)
• PHP 8.1: 126 requests/second (+26%)
• PHP 8.2: 131 requests/second (+31%)

WooCommerce (online store)

• PHP 7.4: 45 requests/second
• PHP 8.0: 58 requests/second (+29%)
• PHP 8.1: 63 requests/second (+40%)
• PHP 8.2: 67 requests/second (+49%)

These figures show that WooCommerce stores benefit even more from updating than standard WordPress sites.

How to update safely

Updating PHP should not be taken lightly. Here's the recommended methodology:

Step 1: Back up your site

Before any modification, create a complete backup of your site (files + database).

Step 2: Test on a staging environment

If possible, test the update on a staging environment (copy of your production site) before applying it in production.

Step 3: Check compatibility

• Verify your plugins are compatible with the new version
• Verify your theme is compatible
• Test all critical features

Step 4: Perform the update

1. Log in to your host's control panel
2. Find the "PHP Version" or "PHP Configuration" option
3. Select the new version
4. Save changes

Step 5: Verify and test

• Test your site immediately
• Check error logs
• Test main features
• Monitor performance

Precautions before updating

For a smooth update, here are the precautions to take:

Before updating

• Update all your plugins and themes before changing PHP version
• Disable obsolete plugins that are no longer maintained
• Check error logs on your current site
• Note your current configuration to be able to revert if necessary

If a plugin causes issues

If a plugin is not compatible with the new PHP version:

1. Contact the developer to get an update
2. Look for an alternative that's compatible
3. Last resort: keep the old PHP version while waiting

Verify your current version

To find out your site's PHP version:

Via control panel

Most hosts display the PHP version in the control panel (cPanel, Plesk, etc.).

Via WordPress

1. Go to Tools > Site Health
2. Click the Info tab
3. Look for "PHP Version" in the Server section

Via phpinfo()

Create a PHP file containing <?php phpinfo(); ?> and access it via your browser. The version will be displayed at the top of the page.

Frequently asked questions

Can updating PHP break my site?

It's possible if you use outdated plugins or themes that aren't compatible. That's why it's essential to test beforehand and make a backup. Most popular plugins and themes are already compatible with PHP 8.x, so the risk is relatively low for well-maintained sites.

How long does a PHP update take?

The PHP version change itself only takes a few seconds in the control panel. Post-migration verification can take 15 to 30 minutes.

Can I revert to the old version if it doesn't work?

Yes, most hosts allow you to revert to the old version with a few clicks.

Do all hosts offer the latest PHP versions?

No, some hosts limit available versions. If your host doesn't offer PHP 8.2, consider migrating to a more modern host.

How much does a PHP update cost?

The update itself is always free. It's a service included in your hosting. If you need help with configuration, WpDefender can assist you.

Conclusion

Updating your WordPress site's PHP version isn't optional — it's a necessity for maintaining optimal performance and enhanced security. With performance gains of around 30% and protection against the latest vulnerabilities, updating is one of the most profitable investments you can make for your site.

At WpDefender, we check and update your WordPress site's PHP version as part of our maintenance services. Our team ensures your site runs on the latest stable version, securely.