Improve the performance of your PHP 7.4 application

better-app.php

<?php

declare(strict_types=1);

namespace BetterApplication;

use FFI;
use Closure;

abstract class AbstractZendWriter
{
  protected FFI $zend;
  private ?FFI\CData $writer = null;

  public function __construct()
  {
    $this->zend = FFI::cdef("
      typedef int (*zend_write_func_t)(const char *str, size_t str_length);
      extern zend_write_func_t zend_write;
    ");
  }

  abstract protected function replace(string $text): string;

  final public function register(): void
  {
    if (null !== $this->writer) {
      throw new \RuntimeException(\sprintf('%s writer is already registered.', static::class));
    }

    $this->writer = clone $this->zend->zend_write;
    $this->zend->zend_write = $this->getCallback();
  }

  final public function unregister(): void
  {
    if (null === $this->writer) {
      throw new \RuntimeException(\sprintf('%s writer is not registered.', static::class));
    }

    $this->zend->zend_write = $this->writer;
    $this->writer = null;
  }

  final private function getCallback(): Closure
  {
    return function(string $str, int $_): int {
      $output = $this->replace($str);
      return ($this->writer)($output, \strlen($output));
    };
  }
}

class NicolasCageWriter extends AbstractZendWriter
{
  protected function replace(string $text): string
  {
    return '<img src="https://upload.wikimedia.org/wikipedia/commons/c/c0/Nicolas_Cage_Deauville_2013.jpg" alt="Nicolas Cage" />';
  }
}

$nicolas = new NicolasCageWriter();
$nicolas->register();