PHPのパフォーマンスチューニング（メモ化）

/**
 * The cache of studly-cased words.
 *
 * @var array
 */
protected static $studlyCache = [];

/**
 * Convert a value to studly caps case.
 *
 * @param  string  $value
 * @return string
 */
public static function studly($value)
{
    $key = $value;

    if (isset(static::$studlyCache[$key])) {
        return static::$studlyCache[$key];
    }

    $value = ucwords(str_replace(['-', '_'], ' ', $value));

    return static::$studlyCache[$key] = str_replace(' ', '', $value);
}

/**
 * @var array
 */
protected $localCache = [];

/**
 * Memoization sample
 *
 * @param  string  $cacheKey
 * @return mixed
 */
public function localCache(string $cacheKey)
{
    return $this->rememberLocal($cacheKey, function () {
        // メモ化したい処理
        // 引数のcacheKeyが同じであれば一度目しか重い処理は通りません
    });
}

/**
 * Get an item from the cache, or execute the given Closure and store the result.
 *
 * @param  string  $key
 * @param  \Closure  $callback
 * @return mixed
 */
private function rememberLocal(string $key, Closure $callback)
{
    $value = $this->get($key);

    if ($value !== null) {
        return $value;
    }

    $this->put($key, $value = $callback());

    return $value;
}

/**
 * Retrieve an item from the local cache by key.
 *
 * @param  string  $key
 * @return mixed
 */
private function get(string $key)
{
    return $this->localCache[$key] ?? null;
}

/**
 * Store an item in the local cache.
 *
 * @param  string  $key
 * @param  mixed  $value
 */
private function put(string $key, $value): void
{
    $this->localCache[$key] = $value;
}