A benchmark of reflection API performance in PHP

reflection-bench.php

<?php

/**
 * Benchmark: Reflection Performance
 *
 * Conclusion: there is no performance-gain from caching reflection-objects.
 */

define('NUM_TESTS', 10);

header('Content-type: text/plain');

$func = function($a, $b, $c) {
  // ...
};

class Foo
{
  public $a;
  protected $b;
  private $c;
  
  public function foo($a,$b,$c) {}
  protected function bar($a,$b,$c) {}
  private function baz($a,$b,$c) {}
}

for ($i=0; $i<NUM_TESTS; $i++) {
  $start = microtime(true);
  $ref = new ReflectionClass($func);
  $end = microtime(true);
  
  echo "ReflectionClass # $i: " . number_format(1000000*($end-$start), 3) . " µsec\n";
}

for ($i=0; $i<NUM_TESTS; $i++) {
  $start = microtime(true);
  $ref = new ReflectionFunction($func);
  $end = microtime(true);
  
  echo "ReflectionFunction # $i: " . number_format(1000000*($end-$start), 3) . " µsec\n";
}

class Cache
{
  private $cache = array();
  
  public function getReflection($class)
  {
    if (!isset($this->cache[$class])) {
      $this->cache[$class] = new ReflectionClass($class);
    }
    return $this->cache[$class];
  }
}

$cache = new Cache;

for ($i=0; $i<NUM_TESTS; $i++) {
  $start = microtime(true);
  $ref = $cache->getReflection('Foo');
  $end = microtime(true);
  
  echo "Cached ReflectionClass # $i: " . number_format(1000000*($end-$start), 3) . " µsec\n";
}

the greater lesson here is "trust the language"

if you don't have a performance problem, don't optimize - especially not preemptively! there's a good chance the language will optimize later, and your "optimizations" become useless complexity, perhaps even slowing things down.

I've seen this happen with lots of things over the years - in different languages, in the browser, it's almost always safer and better in the long run to assume the language is good at what the language is supposed to do. 😄