OPcache is PHP’s built-in bytecode cache — it stores precompiled script bytecode in shared memory, eliminating the need to parse and compile PHP on every request. Enable it in php.ini: opcache.enable=1, opcache.memory_consumption=256, opcache.max_accelerated_files=20000, opcache.validate_timestamps=0 (for production — set to 1 during development). This single change can improve PHP performance by 2-5x. It’s the single most impactful optimization for any PHP application running on a VPS.
OPcache: The Essential Optimization
OPcache is PHP’s built-in bytecode cache — it stores precompiled script bytecode in shared memory, eliminating the need to parse and compile PHP on every request. Enable it in php.ini: opcache.enable=1, opcache.memory_consumption=256, opcache.max_accelerated_files=20000, opcache.validate_timestamps=0 (for production — set to 1 during development). This single change can improve PHP performance by 2-5x. It’s the single most impactful optimization for any PHP application running on a VPS.
PHP-FPM Tuning
PHP-FPM manages PHP worker processes. The key setting is pm = dynamic with appropriate values: pm.max_children controls the maximum number of workers. Calculate based on your VPS RAM: (Total RAM – OS overhead) / average PHP worker memory. For a 4GB VPS with WordPress, typically 20-30 workers. Set pm.start_servers to 25% of max_children, pm.min_spare_servers to 25%, and pm.max_spare_servers to 75%. Monitor with pm.status_path to track active/idle workers.
PHP 8.x JIT Compilation
PHP 8+ includes a JIT (Just-In-Time) compiler that can further improve performance for CPU-intensive operations. Enable with opcache.jit_buffer_size=256M and opcache.jit=1255. JIT provides the most benefit for mathematical computations and CPU-bound workloads. For typical web applications, the improvement is modest (5-15%) on top of OPcache. On FastNode’s UK and European data centers with sub-10ms latency across the UK, optimized PHP delivers blazing-fast page generation.
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