PHP OPcache Explained — Enabled by Default on All AsiaGB Shared Hosting Servers

If your PHP website feels slow despite choosing a decent hosting plan, one of the most common culprits is PHP doing redundant work on every single request. The fastest, cheapest fix — and one that requires zero code changes — is PHP OPcache, an extension bundled with PHP since version 5.5 that most site owners do not know is there.

What Is PHP OPcache and How Does It Work?

To understand OPcache, you first need to understand what PHP does on every request without it. When a browser asks for a page, PHP must perform these steps for every .php file involved:

1. Read the file from disk — PHP opens each .php file from the filesystem. Even with fast SSD storage, reading hundreds of files on every request adds measurable latency.
2. Tokenize / Lex — PHP reads through the source code character by character and breaks it into a stream of tokens: variable names, operators, keywords, string literals.
3. Parse into an AST — The token stream is assembled into an Abstract Syntax Tree that represents the logical structure of the code.
4. Compile to Opcodes — The AST is compiled into low-level Opcodes — the instruction set that the Zend Engine (PHP's execution engine) can run directly.
5. Execute the Opcodes — The Zend Engine runs the Opcodes and produces the HTML output that is sent back to the browser.

The problem is that steps 1 through 4 happen on every request, every time, even though the code has not changed. A typical WordPress page load involves 300–500 PHP files. On a site with 1,000 daily visitors, that means PHP reads and compiles those same files millions of times per day — wasted CPU cycles on work that produces the same result every time.

OPcache eliminates that waste. After PHP compiles a file to Opcodes for the first time, OPcache stores those Opcodes in a shared memory segment (RAM) that all PHP worker processes can access. On the next request for the same file, PHP skips steps 1 through 4 entirely and pulls the ready-to-execute Opcodes straight from RAM. The result: faster TTFB, lower CPU usage, and more concurrent requests handled on the same hardware.

Real-World Performance Numbers

Results vary by application, but these are typical ranges measured on PHP workloads:

Applications with many PHP files per request benefit the most: WordPress with many plugins, WooCommerce stores, Laravel applications with a large vendor directory, and Magento installations with thousands of class files. A simple single-file PHP app or a site already served entirely from page cache will see a smaller delta.

What OPcache does not speed up

Understanding the limits of OPcache is as important as knowing its benefits. OPcache only accelerates PHP code execution. If your site is slow for any of these reasons, OPcache cannot help:

• Slow database queries — Fix with proper indexes, query optimization, or an object cache like Redis.
• External API calls — Dependent on the remote server's response time and network latency.
• Large unoptimized images — Compress and resize images at build time or use a CDN.
• Heavy JavaScript bundles — Use bundling, minification, and code splitting on the frontend.
• Client-side network latency — A CDN with edge nodes closer to your visitors reduces this.

AsiaGB: OPcache Active on Every Shared Hosting Server

What sets AsiaGB shared hosting apart from some providers is that OPcache is not an optional add-on or a premium feature — it is enabled at the system level on every single shared hosting server that AsiaGB operates, across every plan tier.

The rationale is straightforward: OPcache benefits customers by making their sites faster, and it benefits the server by reducing CPU load. Lower CPU pressure across all sites on a server means more headroom for traffic spikes and a better experience for everyone sharing that machine. Enabling OPcache system-wide is a win for both sides.

Settings AsiaGB configures at the system level

AsiaGB pre-configures the core OPcache parameters to values that work well for the shared hosting environment. Customers can override per-account settings through DirectAdmin or .user.ini. Values you may want to customize for your own site:

• opcache.max_accelerated_files — Increase this if your WordPress site has many plugins with large PHP codebases.
• opcache.revalidate_freq — Lower this during active development; raise it on stable production sites.
• opcache.validate_timestamps — Set to 0 on production sites that do not change frequently for maximum speed.

How to Verify OPcache Is Running on Your Site

Even though AsiaGB enables OPcache at the system level, it is good practice to confirm it is active and inspect its current state. Here are the main methods:

Method 1: phpinfo()

Create a file called info.php in your web root with this content:

<?php phpinfo();

Open it in a browser and press Ctrl+F to search for "Zend OPcache". If a section with that name is present and opcache.enable shows On, OPcache is running. Look at the "Cached scripts" statistic to see how many files have already been cached.

Method 2: Check status via PHP code

<?php
if (function_exists('opcache_get_status')) {
    $s = opcache_get_status();
    echo "OPcache enabled: " . ($s['opcache_enabled'] ? 'YES' : 'NO') . "\n";
    echo "Cached scripts: " . $s['opcache_statistics']['num_cached_scripts'] . "\n";
    echo "Hit rate: " . round($s['opcache_statistics']['opcache_hit_rate'], 2) . "%\n";
    echo "Memory used: " . round($s['memory_usage']['used_memory'] / 1048576, 2) . " MB\n";
    echo "Memory free: " . round($s['memory_usage']['free_memory'] / 1048576, 2) . " MB\n";
} else {
    echo "OPcache not available";
}

Method 3: WordPress plugins

Plugins such as LiteSpeed Cache, W3 Total Cache, or Query Monitor display OPcache status in the WordPress dashboard and include a Flush button — no code needed.

Method 4: DirectAdmin

Log in to DirectAdmin › Select PHP Version › check the Extensions list. If opcache has a checkmark next to the PHP version your site uses, it is enabled for your account.

Tuning OPcache for Your Use Case

The right settings depend on your application. Here are recommended configurations for common scenarios:

Standard WordPress site

opcache.enable=1
opcache.memory_consumption=128
opcache.max_accelerated_files=10000
opcache.revalidate_freq=60
opcache.validate_timestamps=1
opcache.interned_strings_buffer=16
opcache.fast_shutdown=1

WordPress + WooCommerce or large plugin-heavy sites

opcache.enable=1
opcache.memory_consumption=256
opcache.max_accelerated_files=20000
opcache.revalidate_freq=120
opcache.validate_timestamps=1
opcache.interned_strings_buffer=32
opcache.max_wasted_percentage=5

Laravel / Symfony on stable production

opcache.enable=1
opcache.memory_consumption=256
opcache.max_accelerated_files=20000
opcache.revalidate_freq=0
opcache.validate_timestamps=0
opcache.interned_strings_buffer=32
opcache.save_comments=1

ini directive	What it controls	Recommendation
opcache.enable	Master on/off switch	Always 1 on production
memory_consumption	MB of RAM allocated for Opcode storage	128 for typical sites, 256 for WooCommerce/Laravel
max_accelerated_files	Maximum number of files OPcache will cache	10000 standard; increase for plugin-heavy WordPress
revalidate_freq	Seconds between file-change checks	60 during development; 0 on stable production
validate_timestamps	Whether to check file modification time at all	1 during development; 0 on stable production
interned_strings_buffer	MB for interned (deduplicated) strings in cached code	16 standard; 32 for large codebases
max_wasted_percentage	% of wasted memory before a cache restart	5 (default is fine)
save_comments	Whether PHP comments/docblocks are preserved in cache	Must be 1 if using Doctrine Annotations or PHP Attributes

PHP JIT: The Next Level on PHP 8.0+

PHP 8.0 introduced JIT (Just-In-Time Compiler), which works on top of OPcache to push performance even further. The key distinction:

• OPcache alone: Stores pre-compiled Opcodes in RAM so the Zend Engine does not re-read or re-compile source files. The Zend Engine still interprets Opcodes one instruction at a time.
• OPcache + JIT: Translates frequently-executed Opcodes into native machine code that the CPU runs directly — no interpreter layer at all.

Enable JIT by adding these directives (PHP 8.0+):

opcache.jit=on
opcache.jit_buffer_size=64M

JIT delivers the largest gains for CPU-intensive work: image processing, mathematical computation, data transformation scripts, and CLI applications. For typical web CRUD applications where the bottleneck is the database rather than CPU, the improvement from JIT is usually small. Benchmark your specific application before enabling JIT in production.

How to Override OPcache Settings on DirectAdmin

AsiaGB configures OPcache at the system level, but you can override individual directives for your own account through DirectAdmin or a .user.ini file:

1. Log in to DirectAdmin — Your DirectAdmin login URL is typically yourdomain.com:2222.
2. Open Select PHP Version — Find this in the Advanced Features or Extra Features section of your dashboard.
3. Confirm OPcache is listed as enabled — In the Extensions tab, opcache should already have a checkmark. If not, enable it and save.
4. Open PHP Options / Settings — Click the Options or Settings tab to access PHP ini overrides for your account.
5. Set your values and save — Changes take effect immediately for new PHP requests.

When and How to Flush the OPcache

OPcache holds compiled Opcodes until certain conditions trigger an invalidation. Knowing when to flush manually is important:

Situations that require a manual cache flush

• WordPress Core, plugin, or theme updates — PHP files change; OPcache may still serve old compiled versions.
• Deploying new application code — Especially critical if validate_timestamps=0.
• Editing PHP files directly via FTP or file manager — Flush after saving to ensure the change takes effect.
• Installing or removing caching plugins — These often register hooks that PHP needs to re-compile.

Methods to flush OPcache

Method	Command / Step	Best for
PHP function	opcache_reset(); in a protected script	Deployment scripts, CLI automation
WordPress plugin	LiteSpeed Cache › Flush OPcache button	Non-developers managing WordPress
SSH (if available)	php -r "opcache_reset();"	Developers with SSH access
Restart PHP-FPM	DirectAdmin › Restart Services	Emergency full reset
Automatic via timestamps	validate_timestamps=1 + revalidate_freq=60	Sites that update frequently and tolerate a 60-second lag

Monitoring OPcache Health

On production sites, tracking two OPcache metrics tells you whether the cache is working optimally:

1. Memory usage

If used memory exceeds roughly 80% of the allocated memory_consumption value, OPcache starts evicting cached files, forcing PHP to recompile them. Check with opcache_get_status() and increase memory_consumption if utilization is consistently high.

2. Cache hit rate

A healthy hit rate is above 90%. Below that threshold, files are being evicted too frequently. The fix is either more memory or a reduced max_accelerated_files count so the cache stays within budget.

<?php
$s = opcache_get_status();
$stats = $s['opcache_statistics'];
echo "Hit rate: " . round($stats['opcache_hit_rate'], 2) . "%\n";
echo "Cached: " . $stats['num_cached_scripts'] . " files\n";
echo "Evicted: " . $stats['num_cached_keys'] - $stats['num_cached_scripts'] . " files\n";
echo "Memory: " . round($s['memory_usage']['used_memory']/1048576,1)
   . " MB used / " . round($s['memory_usage']['free_memory']/1048576,1) . " MB free\n";

OPcache vs Other Caching Layers: They Are Complementary, Not Alternatives

OPcache is one layer in a complete caching stack. Each layer addresses a different bottleneck:

Cache type	What it caches	What it speeds up	Examples
OPcache	PHP compiled bytecode (Opcodes)	PHP execution speed	Zend OPcache (built-in)
Object Cache	Database query results, computed values	Database round-trips	Redis, Memcached
Page Cache	Fully rendered HTML pages	Bypasses PHP entirely (fastest)	LiteSpeed Cache, W3 Total Cache
CDN / Edge Cache	Static assets (CSS, JS, images)	Reduces latency via edge nodes near users	Cloudflare, BunnyCDN
Browser Cache	Static assets on the client device	Eliminates repeated downloads	Cache-Control headers

The ideal WordPress performance stack combines all five layers: OPcache for PHP execution → Object Cache (Redis) for database queries → Page Cache for serving pre-built HTML → CDN for static assets → Browser Cache headers. OPcache is the first layer to enable because it is free, has no side effects on most sites, and is already active on all AsiaGB servers.

PHP OPcache: PHP 7.4 vs PHP 8.x

If you are still on PHP 7.4, here is how OPcache compares across versions:

Feature	PHP 7.4	PHP 8.0+
Core OPcache	Yes — full feature set	Yes — full feature set
JIT Compiler	No	Yes (opcache.jit)
Preloading	Yes (opcache.preload)	Yes — improved
fast_shutdown	Must be set to 1 manually	Automatic
Security support	End of life Nov 2022	PHP 8.3 supported until Nov 2026; PHP 8.2 until Dec 2025

AsiaGB recommends PHP 8.1 or higher for all new projects. It is faster than PHP 7.x, has longer security support, and unlocks JIT along with other PHP 8 improvements. You can switch your PHP version at any time via DirectAdmin without affecting your site's files.

Troubleshooting Common OPcache Issues

Problem: I edited a PHP file but the change is not showing

OPcache is still serving the old compiled version. Either wait for the revalidate_freq window to expire, call opcache_reset(), or flush via your plugin. If this happens frequently during development, set validate_timestamps=1 and reduce revalidate_freq to a low value like 2.

Problem: My site became slower after enabling OPcache

This is unusual but can happen if memory_consumption is set too low. OPcache runs out of space and evicts frequently, causing constant recompilation. Check the hit rate — if it is below 90%, increase memory_consumption.

Problem: "Cannot allocate memory" errors in PHP logs

OPcache is out of memory. Increase memory_consumption or reduce max_accelerated_files. You can also run opcache_reset() to clear the cache and start fresh.

Problem: Doctrine Annotations / PHP Attributes stopped working

Ensure opcache.save_comments=1 (this is the default). Doctrine and some frameworks read PHP docblock comments at runtime for annotation processing. If comments are stripped from the cache, these frameworks break.

Frequently Asked Questions

Does AsiaGB enable OPcache automatically on shared hosting?

Yes. AsiaGB enables PHP OPcache on every shared hosting server by default across all plans. Customers do not need to turn it on manually or pay extra. Servers are pre-configured with OPcache at the system level. You can further customize settings via DirectAdmin.

Do I need root access to configure OPcache?

No. On DirectAdmin hosting you can adjust OPcache settings through the PHP Version selector in your control panel, or by adding a .user.ini file to your web root, without needing root or SSH access.

What is the difference between OPcache and Redis?

OPcache caches compiled PHP bytecode to accelerate code execution. Redis is an object cache that stores database results and computed data to reduce MySQL queries. They work at different layers and are best used together.

Will OPcache use more RAM?

Yes, OPcache reserves a block of shared memory (typically 128 MB via memory_consumption). On AsiaGB shared hosting, servers are designed with OPcache RAM requirements already accounted for, so it does not count against your account's storage quota.

What is PHP JIT and does AsiaGB support it?

JIT is a PHP 8.0+ feature that compiles frequently-used Opcodes into native machine code for even faster execution. AsiaGB supports PHP 8.0 through 8.3, all of which include JIT. You can enable it via DirectAdmin PHP settings or .user.ini.