drupal_lookup_path() optimization: Load path table on array

I have seen different options to make drupal_lookup_path() method faster, but no one was fast enough for me. On my hosting, Dreamhost currently, DB queries take too long when server has a lot of visits and simple queries as looking for a path take between 10 and 40 miliseconds, which is a lot if you have to check hundreds of paths.

Since my site doesn't have a high number of url aliases (currently less than 100) I have modified the code to load the whole table the first time this method is called, so subsequent calls won't go to DB at all.

Based on Devel module, I have reduced the amount of queries from 300 to 91 on an average forum page. This means the same page is being generated now in less than one second instead of 3 or 4 seconds it was taking before.

Here is the code:

function drupal_lookup_path($action, $path = '') {
  static $map = array();

  if ($action == 'wipe')
  {
    $map = array();
    return FALSE;
  }

  if ($path != '')
  {
    // Initial load from DB
    if (count($map) == 0) {
    	$result = db_query("SELECT src, dst FROM {url_alias}");
    	while ($url = db_fetch_object($result)) {
    		$map[$url->src] = $url->dst;
    		$map[$url->dst] = $url->src;
    	}
    }
    // $action == 'alias' or $action == 'source'
    if (isset($map[$path])) return $map[$path];
  }

  return FALSE;
}

I load the array in both ways, from src to dst and dst to src which means the array will have twice the records your alias table has.

BTW, my website is www.spaniards.es.