--- path.inc	2009-04-07 22:35:47.000000000 +0000
+++ path.inc	2009-04-08 18:53:24.000000000 +0000
@@ -44,6 +44,93 @@ function drupal_lookup_path($action, $pa
   static $map = array(), $no_src = array();
   static $count;
 
+  $path_language = '';
+// ************* Begin pathcache.module Path Caching Modifications **************
+
+  // Drupal core checks to see if the url_alias table is empty on each request.
+  // We assume that the table is nonempty, since it would be very silly to enable
+  // the Path Cache module if you had no paths to cache. Thus, we have eliminated
+  // the $count variable altogether.
+  /* 
+  
+  // Use $count to avoid looking up paths in subsequent calls if there simply are no aliases
+  if (!isset($count)) {
+    $count = (int)db_result(db_query('SELECT pid FROM {url_alias} LIMIT 1'));
+  }
+  */
+
+  // A wipe is most commonly performed by path_set_alias() in path.module via 
+  // drupal_clear_path_cache() in common.inc. The intent it to clear the static
+  // variables $map and $no_src, but we can also use it as an indicator that
+  // the path cache is dirty.
+  if ($action == 'wipe') {
+    $map = array();
+    $no_src = array();
+    // This will flush the entire cache_path cache.
+    // Drastic, but if running with a memcached caching backend, wildcards
+    // are not supported so the whole bin must be flushed.
+    cache_clear_all('pathdst*', 'cache', TRUE);
+    cache_clear_all('pathsrc*', 'cache', TRUE);
+  }
+  elseif ($path != '') {
+    // When action is 'alias' we are given a Drupal path and are looking to
+    // see if there is an alias for it.
+    if ($action == 'alias') {
+      // First check the static variable in case we've looked up this system path earlier
+      // in this request.
+      if (isset($map[$path_language][$path])) {
+        return $map[$path_language][$path];
+      }
+      // Not in the static variable. Try cache.
+      $cid = $path . $path_language;
+      $cache = cache_get('pathdst'.$cid, 'cache');
+      if ($cache) {
+        return unserialize($cache->data);
+      }
+      // Get the most fitting result falling back with alias without language.      
+      $alias = db_result(db_query("SELECT dst FROM {url_alias} WHERE src = '%s'", $path));
+      // Store in static variable in case we encounter the same system path again
+      // during this request.
+      $map[$path_language][$path] = $alias;
+      // Store in cache.
+      cache_set('pathdst'.$cid, 'cache', serialize($alias), variable_get('pathcache_expire', 43200)); // 12 hours
+      return $alias;
+    }
+    // When action is 'source' we are given a URL alias and need to return the
+    // Drupal path.
+    // Check $no_src for this $path in case we've already determined that there
+    // isn't a path that has this alias.
+    elseif ($action == 'source' && !isset($no_src[$path_language][$path])) {
+      $src = '';
+      // Look for the value $path within the cached $map.
+      if (!isset($map[$path_language]) || !($src = array_search($path, $map[$path_language]))) {
+        $cid = $path . $path_language;
+        $cache = cache_get('pathsrc'.$cid, 'cache');
+        if ($cache) {
+          return unserialize($cache->data);
+        }
+        
+        // Get the most fitting result falling back with alias without language
+        if ($src = db_result(db_query("SELECT src FROM {url_alias} WHERE dst = '%s'", $path))) {
+          $map[$path_language][$src] = $path;
+          cache_set('pathsrc'.$cid, 'cache', serialize($src), variable_get('pathcache_expire', 43200)); // 12 hours
+        }
+        else {
+          // We can't record anything into $map because we do not have a valid
+          // index and there is no need because we have not learned anything
+          // about any Drupal path. Thus cache to $no_src.
+          // Setting this flag makes the array_search($path, $map[$path_language]) test
+          // above false, and skips to return $src, below.
+          $no_src[$path_language][$path] = TRUE;
+        }
+      }
+      return $src;
+    }
+  }
+
+  return FALSE;    
+  // ************** End pathcache.module Path Caching Modifications ***************  
+  
   // Use $count to avoid looking up paths in subsequent calls if there simply are no aliases
   if (!isset($count)) {
     $count = db_result(db_query('SELECT COUNT(pid) FROM {url_alias}'));