Updating PHP in cPanel: Impact on WordPress Speed and Compatibility

If you’re running WordPress on shared hosting, chances are you’re dealing with cPanel for server management. One of the most impactful yet overlooked optimizations you can make is updating your PHP version. Let’s dive into how this affects your WordPress site’s performance, WordPress compatibility, and what you need to watch out for.

Why PHP Version Matters for WordPress

PHP is the backbone of WordPress; every page load, every database query, and every plugin interaction runs through PHP. Using an outdated version is like running modern software on a decade-old computer. You’ll get the job done, but not efficiently.

Here’s the reality: PHP 8.3 can be up to 3x faster than PHP 7.4 for WordPress sites. That’s not just a marginal improvement; that’s the difference between a site that loads in 1.2 seconds versus 3.6 seconds.

Performance Impact: The Numbers

Based on average WordPress compatibility with standard plugins and themes

The performance gains come from several improvements:

• Just-In-Time (JIT) compilation in PHP 8.0+
• Better opcode caching and memory management
• Optimized string handling and array operations
• Reduced function call overhead

How to Update PHP in cPanel

Step 1: Check Current PHP Version

Before making changes, document what you’re currently running:

1. Log in to your cPanel dashboard
2. Look for “Select PHP Version” or “PHP Selector” (varies by host)
3. Note your current version and any enabled extensions

Alternatively, create a quick PHP info file:

<?php

phpinfo();

?>

Upload this as phpinfo.php to your site root and visit yourdomain.com/phpinfo.php.

Step 2: Back Up Everything

This isn’t optional. Before touching PHP versions:

• Full site backup (files + database)
• Export your current PHP configuration
• List of active plugins (screenshot works fine)

Step 3: Update PHP Version

1. In cPanel, find “Select PHP Version” or similar
2. Choose your target version (I recommend PHP 8.2 for stability)
3. Click “Set as current.”
4. Don’t apply yet, we need to configure extensions first

Step 4: Configure PHP Extensions

WordPress needs specific PHP extensions to function properly. Enable these essentials:

Required Extensions:

• mysqli or mysqlnd (database connectivity)
• curl (HTTP requests, API calls)
• gd or imagick (image processing)
• zip (plugin/theme installations)
• mbstring (multibyte string handling)
• xml (XML parsing)
• json (JSON handling)

Recommended Extensions:

• opcache (significant performance boost)
• intl (internationalization)
• bcmath (precise calculations)
• exif (image metadata)

Step 5: Apply and Test

Hit “Apply” and immediately test your site:

• Frontend loading (homepage, posts, pages)
• Admin dashboard access
• Plugin functionality (especially contact forms, caching, SEO)
• Theme features (sliders, galleries, custom post types)

Compatibility Issues to Watch For

Common Plugin Problems

Some plugins lag behind PHP updates. Here’s what typically breaks:

Deprecated Function Calls: Older plugins using removed PHP functions will throw fatal errors. Common culprits:

• Contact form plugins using mysql_* functions
• Old SEO plugins with deprecated string functions
• Legacy e-commerce extensions

Memory Limit Issues: PHP 8+ can be more memory-efficient but also stricter about memory allocation. You might need to increase your memory limit:

ini_set(‘memory_limit’, ‘256M’);

Theme Compatibility

Custom themes, especially older ones, might have issues with:

• Deprecated jQuery methods (if theme includes custom JavaScript)
• PHP syntax changes (older array syntax, variable handling)
• Image processing differences between PHP versions

Database Connection Problems

If you see “Error establishing database connection” after updating, check:

• MySQL version compatibility
• Connection charset settings
• Database user permissions

Troubleshooting Common Issues

Fatal Error: Can’t Access Site

If your site goes down completely:

1. Revert PHP version immediately in cPanel
2. Check error logs (cPanel > Error Logs)
3. Identify the problematic plugin/theme
4. Update or replace the incompatible component
5. Try the PHP update again

Site Loads, But Features Broken

For partial functionality issues:

1. Deactivate all plugins and test
2. Switch to default theme (Twenty Twenty-Four)
3. Reactivate plugins one by one to identify the culprit
4. Check plugin/theme update availability

Performance Regression

If your site gets slower after updating:

• Enable OPcache if not already active
• Check memory limit settings
• Review caching plugin compatibility
• Monitor server resources for unusual spikes

Post-Update Optimization

Once you’ve successfully updated, maximize the benefits:

Enable OPcache

If your host allows it, enable OPcache for dramatic performance improvements:

opcache.enable=1

opcache.memory_consumption=128

opcache.max_accelerated_files=4000

Update WordPress and Plugins

Newer PHP versions work best with updated software:

• Update WordPress core to the latest version
• Update all plugins and themes
• Remove unused plugins to reduce compatibility risks

Monitor Performance

Use tools to measure the impact:

• GTmetrix or Google PageSpeed Insights for load times
• Query Monitor plugin for database performance
• Server response time monitoring

Best Practices for PHP Updates

Staging Environment

If possible, test PHP updates on a staging site first. Many hosts offer staging environments, or you can create a subdomain for testing.

Gradual Updates

Don’t jump from PHP 7.4 straight to 8.3. Try:

1. PHP 7.4 → 8.0
2. Test thoroughly
3. PHP 8.0 → 8.1
4. Test again
5. Continue incrementally

Regular Maintenance

• Check PHP version quarterly
• Update within 6 months of new stable releases
• Monitor security announcements for your current version
• Keep plugin/theme inventory updated

When NOT to Update

Hold off on PHP updates if:

• Critical business period (holidays, launches)
• Using very old plugins that can’t be updated
• Custom code that hasn’t been reviewed for compatibility
• No backup/staging capability

Wrapping Up

Updating PHP in cPanel isn’t just about staying current; it’s about giving your WordPress site the performance boost it deserves. The speed improvements are real and significant, but the key is doing it methodically.

Take your time, test thoroughly, and don’t be afraid to roll back if something breaks. Your future self (and your site visitors) will thank you for the faster loading times and improved user experience.

Remember: a 2-second improvement in load time can increase conversions by up to 15%. That’s worth a careful PHP update process.