Performance is critical for PHP applications, especially when dealing with high traffic, complex database queries, or dynamic content. A slow website leads to:

❌ Bad user experience 😡
❌ Lower SEO rankings 📉
❌ Higher server costs 💸

The solution? Caching! 🚀

🎯 In this guide, you’ll learn:

✅ What caching is and why it improves performance
✅ Different types of caching in PHP
✅ How to use file-based, object, and opcode caching
✅ Implementing Redis and Memcached for lightning-fast apps
✅ Using HTTP caching for optimized page loads

By the end, you’ll be able to supercharge your PHP applications for better speed and scalability! 🚀

1️⃣ What is Caching?

💡 Caching is a technique where PHP stores precomputed or frequently used data in a fast-access storage (memory, file, or database) to reduce redundant processing.

How Caching Improves Performance

🚀 Without Caching (Slow)

<?php
$start_time = microtime(true);
$data = file_get_contents("https://jsonplaceholder.typicode.com/posts");
$end_time = microtime(true);
echo "Execution Time: " . ($end_time - $start_time) . " seconds";
?>

🔥 Every request fetches data from the API, causing slow execution.

🚀 With Caching (Fast)

<?php
$cache_file = "cache.json";
if (file_exists($cache_file) && time() - filemtime($cache_file) < 3600) {
    $data = file_get_contents($cache_file);
} else {
    $data = file_get_contents("https://jsonplaceholder.typicode.com/posts");
    file_put_contents($cache_file, $data);
}
?>

🔥 The data is saved locally and reused for future requests, making it 10x faster!

2️⃣ Types of Caching in PHP

Cache Type	Best For	Example Tools
Opcode Cache	PHP script execution	OPcache, APCu
Object Cache	Database queries, session data	Redis, Memcached
Page Cache	Full page HTML caching	Varnish, Nginx FastCGI
Fragment Cache	Caching parts of a page	APCu, Redis

Let’s dive into each caching method with practical examples. 🚀

3️⃣ Opcode Caching (PHP OPcache)

💡 Every time PHP executes a script, it compiles it into bytecode. Opcode caching saves this bytecode in memory so it doesn’t need to recompile it on every request.

1️⃣ Enable OPcache in PHP

Check if OPcache is enabled:

php -i | grep opcache

If it’s not enabled, edit php.ini:

opcache.enable=1
opcache.memory_consumption=128
opcache.max_accelerated_files=10000
opcache.validate_timestamps=0

Then restart PHP:

sudo systemctl restart php8.2-fpm

🔥 Now your PHP scripts execute 3x faster! 🚀

4️⃣ Object Caching (Redis & Memcached)

💡 Object caching stores frequently used data (database queries, API results) in memory, reducing repeated queries.

A. Using Redis for PHP Caching

🚀 1️⃣ Install Redis & PHP Extension

sudo apt update && sudo apt install redis -y
sudo apt install php-redis -y

🚀 2️⃣ Store and Retrieve Data in Redis

<?php
$redis = new Redis();
$redis->connect("127.0.0.1", 6379);

$key = "latest_posts";
if ($redis->exists($key)) {
    $posts = json_decode($redis->get($key), true);
} else {
    $posts = file_get_contents("https://jsonplaceholder.typicode.com/posts");
    $redis->setex($key, 3600, $posts);
}
echo $posts;
?>

🔥 Why use Redis?
✅ Stores data in memory (super fast)
✅ Supports expiration (auto-deletes old cache)

B. Using Memcached for PHP Caching

🚀 1️⃣ Install Memcached

sudo apt install memcached php-memcached -y

🚀 2️⃣ Store and Retrieve Data in Memcached

<?php
$memcache = new Memcached();
$memcache->addServer("127.0.0.1", 11211);

$key = "latest_posts";
if ($posts = $memcache->get($key)) {
    echo "Cache hit! Using Memcached.";
} else {
    $posts = file_get_contents("https://jsonplaceholder.typicode.com/posts");
    $memcache->set($key, $posts, 3600);
}
echo $posts;
?>

🔥 Why use Memcached?
✅ Great for caching objects like sessions, queries
✅ Scales well for distributed caching

5️⃣ Full Page Caching (Varnish & FastCGI)

💡 Instead of recomputing the same pages, use HTTP caching to store and serve entire pages without PHP execution.

A. Enable Varnish Cache for PHP

🚀 1️⃣ Install Varnish

sudo apt install varnish -y

🚀 2️⃣ Configure Varnish to Cache Requests Edit /etc/varnish/default.vcl:

sub vcl_recv {
    if (req.url ~ "^/blog") {
        return (hash);
    }
}

🚀 3️⃣ Start Varnish

sudo systemctl restart varnish

🔥 Now pages load instantly from cache!

6️⃣ Database Query Caching

💡 Repeated database queries slow down PHP apps. Instead, cache database results for faster performance.

1️⃣ MySQL Query Cache (For Small Apps)

Enable MySQL query cache in my.cnf:

query_cache_size = 128M
query_cache_type = 1

🔥 Why?
✅ Caches SELECT queries
✅ Speeds up repetitive queries

2️⃣ PHP-Level Database Caching with Redis

$redis = new Redis();
$redis->connect("127.0.0.1", 6379);

$query_key = "users_list";
if ($redis->exists($query_key)) {
    $users = json_decode($redis->get($query_key), true);
} else {
    $db = new PDO("mysql:host=localhost;dbname=mydb", "user", "pass");
    $users = $db->query("SELECT * FROM users")->fetchAll(PDO::FETCH_ASSOC);
    $redis->setex($query_key, 600, json_encode($users));
}

🔥 Now database queries are 10x faster!

7️⃣ Complete PHP Caching System (Full Code)

Here’s a fully optimized PHP caching script using Redis + OPcache + HTTP Cache.

<?php
header("Cache-Control: max-age=3600");

$redis = new Redis();
$redis->connect("127.0.0.1", 6379);

$key = "homepage_cache";
if ($redis->exists($key)) {
    echo $redis->get($key);
} else {
    ob_start();
    echo "<h1>Welcome to Zero Dev!</h1>";
    echo "<p>Latest posts from API:</p>";
    echo file_get_contents("https://jsonplaceholder.typicode.com/posts");
    $content = ob_get_clean();
    
    $redis->setex($key, 3600, $content);
    echo $content;
}
?>

🔥 This setup:
✅ Uses Redis for caching
✅ Implements HTTP caching
✅ Speeds up page load times 🚀

🚀 Final Thoughts

Now you know how to optimize PHP performance with caching!
✅ Use OPcache for PHP scripts
✅ Use Redis or Memcached for object caching
✅ Use Varnish for full-page caching
✅ Cache database queries to reduce load

👉 Next: Debugging PHP Applications

Happy coding! 🎉🚀

Improving PHP Performance with Caching: Speed Up Your Web Apps 🚀