📊 20. Performance Optimization (PHP)

Improving PHP performance is critical for faster websites, better SEO, and lower server costs.

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⚡ 1. Caching

Caching stores precomputed results so PHP doesn’t need to process the same request again.

🔹 Types of Caching:

✅ 1. Output Caching

Stores full HTML output.

ob_start();// Your PHP logic
echo "Hello World";file_put_contents("cache/page.html", ob_get_contents());
ob_end_flush();

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✅ 2. File Caching

Save data in files to avoid repeated DB queries.

$cacheFile = 'cache/data.json';if (file_exists($cacheFile)) {
    $data = json_decode(file_get_contents($cacheFile), true);
} else {
    $data = getDataFromDatabase();
    file_put_contents($cacheFile, json_encode($data));
}

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✅ 3. Memory Caching (Best Performance)

Use tools like:

• Redis
• Memcached

$redis = new Redis();
$redis->connect('127.0.0.1', 6379);$key = "users";if ($redis->exists($key)) {
    $users = json_decode($redis->get($key), true);
} else {
    $users = getUsersFromDB();
    $redis->set($key, json_encode($users), 60);
}

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🚀 2. OPcache

OPcache stores compiled PHP bytecode in memory, so scripts don’t need to be recompiled on every request.

🔹 Enable OPcache

In php.ini:

opcache.enable=1
opcache.memory_consumption=128
opcache.max_accelerated_files=10000
opcache.revalidate_freq=2

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🔹 Check OPcache Status

<?php
print_r(opcache_get_status());
?>

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🔹 Benefits:

• ⚡ Faster execution
• 🔥 Reduced CPU usage
• 📉 Lower server load

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🧠 3. Code Optimization

Writing efficient PHP code is equally important.

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✅ Avoid Unnecessary Loops

❌ Bad:

for ($i = 0; $i < count($arr); $i++) {

✅ Good:

$len = count($arr);
for ($i = 0; $i < $len; $i++) {

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✅ Use Built-in Functions

❌ Bad:

$len = 0;
while(isset($str[$len])) $len++;

✅ Good:

$len = strlen($str);

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✅ Minimize Database Queries

❌ Bad:

foreach ($users as $user) {
    getUserDetails($user['id']);
}

✅ Good:

SELECT * FROM users WHERE id IN (...);

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✅ Use Prepared Statements

$stmt = $pdo->prepare("SELECT * FROM users WHERE id = ?");
$stmt->execute([$id]);

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✅ Avoid Including Files Multiple Times

require_once 'config.php';

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✅ Use Proper Data Structures

• Arrays vs Objects wisely
• Use isset() instead of array_key_exists() when possible (faster)

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✅ Turn Off Error Display in Production

display_errors = Off
log_errors = On

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🔥 Pro Tips (Advanced)

• Use Gzip Compression

ob_start("ob_gzhandler");

• Enable HTTP caching headers

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

• Use CDN for static assets
• Optimize images & CSS/JS

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🎯 Summary

Technique	Impact
Caching	🔥 Very High
OPcache	⚡ High
Code Optimization	🚀 Medium