PHP 8.4 Performance Gains for WordPress: What Site Owners Should Expect

PHP 8.4 landed in November 2024, and WordPress site owners are asking the obvious question: How much faster will my site be? The honest answer might surprise you. While benchmark numbers show improvement, the real-world gains are more modest than marketing headlines suggest. Here’s what you should actually expect, and whether upgrading makes sense for your site right now.

Performance Reality Check

Let’s start with the numbers. Independent benchmarks from Kinsta show measurable improvements, but context matters more than raw data.

WordPress PHP Version Performance Comparison

PHP Version	WordPress Requests/Second	vs PHP 7.4
PHP 7.4	139.06 req/s	Baseline
PHP 8.2	146.09 req/s	+5.1%
PHP 8.3	142.75 req/s	+2.7%
PHP 8.4	148.22 req/s	+6.6%

Test conditions: ApacheBench, 15 concurrent requests, OPcache enabled, JIT disabled. Source: Kinsta PHP Benchmarks.

The key insight? If you’re still on PHP 7.4, upgrading to PHP 8.4 delivers roughly 6.6% improvement. That’s meaningful. But if you’re already running PHP 8.2 or 8.3, the gains shrink to 1-3%, which most visitors won’t notice.

You may have heard about PHP 8.4’s improved JIT (Just-In-Time compilation). The reality: JIT optimizes CPU-intensive calculations, but WordPress spends most of its time waiting on database queries and file operations. Tideways benchmarks confirm this, showing only a 3.5% difference with JIT enabled versus disabled. Leave JIT on (it’s the default), but don’t expect it to transform your page load times.

Bottom line: Upgrade from PHP 7.x for real gains. Upgrade from PHP 8.x primarily for security and compatibility, not speed.

WordPress Compatibility Status

WordPress 6.7 and later include beta support for PHP 8.4. What does “beta” mean in practice? Core WordPress functions work correctly, but some edge cases may trigger deprecation notices. For most sites, this won’t cause problems.

The plugin ecosystem is the bigger variable. Well-maintained plugins from reputable developers have largely updated for PHP 8.4 compatibility. Abandoned or poorly-coded plugins may throw errors. Before upgrading, check when your critical plugins were last updated. If a plugin hasn’t been touched in two years, test carefully in staging.

WooCommerce users need version 10.4.2 or higher for stable PHP 8.4 support. Earlier versions had PHP 8.4 compatibility issues that triggered errors during checkout. If you’re running an online store, verify your WooCommerce version before making the switch.

Hosting Provider Readiness

Most managed WordPress hosts now offer PHP 8.4, though rollout timing varies.

Major Hosting Provider PHP 8.4 Availability

Host	PHP 8.4 Status	Notes
Kinsta	Available (Dec 2024)	One-click switching in dashboard
SiteGround	Available (Nov 2024)	Available in Site Tools
WP Engine/WP Cloud	Available	Forced upgrade to PHP 8.4 by Dec 31, 2025

A critical deadline to note: PHP 8.1 reaches end-of-life on December 31, 2025. After that date, no security patches. If your host still runs PHP 8.1, you’ll need to upgrade within the next year regardless of performance considerations. Check your current PHP version in your hosting dashboard, most hosts display it prominently.

Should You Upgrade Now?

The answer depends on your current situation. Here’s a practical decision framework:

Upgrade Now If:

• You’re still on PHP 7.4 (security risk, noticeable performance gains available)
• Your host has already switched you to PHP 8.4 or will force it soon
• You’ve tested in staging without errors
• Your plugins are actively maintained and recently updated

Wait 3-6 Months If:

• You’re on PHP 8.2 or 8.3 with no compatibility issues
• Your site relies heavily on older plugins that haven’t been updated
• You run a high-traffic ecommerce site and prefer proven stability
• You don’t have a staging environment to test safely

Pre-Upgrade Checklist:

1. Check your current PHP version in your hosting dashboard
2. Verify WordPress is version 6.7 or higher
3. Update all plugins and themes to latest versions
4. If running WooCommerce, confirm version 10.4.2+
5. Create a full site backup
6. Test on staging environment first (if available)
7. Monitor error logs for 24-48 hours after upgrading

For sites already on PHP 8.2 or 8.3, upgrading is more about staying current than chasing speed. The performance difference is minimal. But with PHP 8.1’s end-of-life approaching, planning your upgrade path now prevents a scramble later.

If you rely on a specific plugin that hasn’t declared PHP 8.4 support, reach out to the developer or check their support forums. Most actively maintained plugins work fine, but confirmation provides peace of mind.

What This Means for Your Site

PHP 8.4 is a solid release that improves security, adds developer features, and delivers modest performance gains. For site owners, the honest summary is this: you’ll see meaningful improvement only if you’re upgrading from PHP 7.x. Those already on recent PHP 8.x versions should upgrade for security and future-proofing, not speed.

The PHP 8.1 end-of-life deadline in December 2025 creates natural urgency. If you haven’t upgraded recently, now is a good time to plan your move. Test in staging, update your plugins, and make the switch when you’re confident everything works.

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Sources: Kinsta PHP Benchmarks, Tideways PHP 8.4 Performance Analysis, WordPress PHP Compatibility Handbook