diff -urp ./includes/common.inc ../drupal-6.2-patched/includes/common.inc
--- ./includes/common.inc       2008-04-09 21:11:44.000000000 +0000
+++ ../drupal-6.2-patched/includes/common.inc   2008-05-13 15:45:46.000000000 +0000
@@ -1463,6 +1463,7 @@ function drupal_page_footer() {
   if (variable_get('cache', CACHE_DISABLED) != CACHE_DISABLED) {
     page_set_cache();
   }
+  drupal_lookup_path('cache');
 
   module_invoke_all('exit');
 }
diff -urp ./includes/path.inc ../drupal-6.2-patched/includes/path.inc
--- ./includes/path.inc 2007-11-04 16:42:45.000000000 +0000
+++ ../drupal-6.2-patched/includes/path.inc     2008-05-13 15:45:46.000000000 +0000
@@ -45,51 +45,103 @@ function drupal_init_path() {
  */
 function drupal_lookup_path($action, $path = '', $path_language = '') {
   global $language;
-  // $map is an array with language keys, holding arrays of Drupal paths to alias relations
-  static $map = array(), $no_src = array(), $count;
+  static
+    $map, $no_src,
+    $map_dirty = FALSE, $no_src_dirty = FALSE,
+    $count, $expire = 0;
+  global $base_root;
 
   $path_language = $path_language ? $path_language : $language->language;
 
   // 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}'));
+    $count = db_result(db_query('SELECT COUNT(*) FROM {url_alias}'));
   }
+  if ($count == 0) {
+    return FALSE;
+  }
+  if (!isset($map)) {
+    $cache = cache_get('map_'. $base_root . request_uri(), 'cache_path');
+    if ($cache) {
+      // FIXME: Why isn't un/serialization consistant?
+      if (is_array($cache->data)) {
+        $map = $cache->data;
+      }
+      else {
+        $map = unserialize($cache->data);
+      }
+      $expire = $cache->expire;
+    }
+    else {
+      $map = array();
+    }
 
-  if ($action == 'wipe') {
-    $map = array();
-    $no_src = array();
-  }
-  elseif ($count > 0 && $path != '') {
-    if ($action == 'alias') {
-      if (isset($map[$path_language][$path])) {
-        return $map[$path_language][$path];
-      }
-      // Get the most fitting result falling back with alias without language
-      $alias = db_result(db_query("SELECT dst FROM {url_alias} WHERE src = '%s' AND language IN('%s', '') ORDER BY language DESC", $path, $path_language));
-      $map[$path_language][$path] = $alias;
-      return $alias;
+    $cache = cache_get('no_src_'. $base_root . request_uri(), 'cache_path');
+    if ($cache) {
+      // FIXME: Why isn't un/serialization consistant?
+      if (is_array($cache->data)) {
+        $no_src = $cache->data;
+      }
+      else {
+        $no_src = unserialize($cache->data);
+      }
+      $expire = $cache->expire;
     }
-    // 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])) {
-      // Look for the value $path within the cached $map
-      $src = '';
-      if (!isset($map[$path_language]) || !($src = array_search($path, $map[$path_language]))) {
-        // 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' AND language IN('%s', '') ORDER BY language DESC", $path, $path_language))) {
-          $map[$path_language][$src] = $path;
+    else {
+      $no_src = array();
+    }
+  }
+  switch ($action) {
+    case 'alias':
+      if ($count > 0 && $path) {
+        if (isset($map[$path])) {
+          return $map[$path];
+          }
+        if (!$alias = db_result(db_query("SELECT dst FROM {url_alias} WHERE src = '%s'", $path))) {
+          $alias = FALSE;
+          }
+        $map[$path] = $alias;
+        $map_dirty = TRUE;
+        return $alias;    
         }
-        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.
-          $no_src[$path_language][$path] = TRUE;
+      break;
+    case 'source':
+      // Check $no_src for this $path in case we've already determined that there
+      // isn't a path that has this alias
+      if ($count > 0 && $path && !isset($no_src[$path])) {
+        if (!$src = array_search($path, $map)) {
+          if ($src = db_result(db_query("SELECT src FROM {url_alias} WHERE dst = '%s'", $path))) {
+            $map[$src] = $path;
+            $map_dirty = TRUE;
+          }
+          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.
+            $no_src[$path] = TRUE;
+            $no_src_dirty = TRUE;
+            return FALSE;
+          }
         }
+        return $src;
       }
-      return $src;
-    }
+    break;
+    case 'wipe':
+      $map = array();
+      $no_src = array();
+      break;
+    case 'cache':
+      if (!$expire) {
+        $expire = time() + (60 * 60 * 24);
+      }
+      if ($map_dirty) {
+        cache_set('map_'. $base_root . request_uri(), $map, 'cache_path', $expire);
+      }
+      if ($no_src_dirty) {
+        cache_set('no_src_' . $base_root . request_uri(), $no_src, 'cache_path', $expire);
+      }
+      break;
   }
-
   return FALSE;
 }
 
diff -urp ./modules/path/path.module ../drupal-6.2-patched/modules/path/path.module
--- ./modules/path/path.module  2008-04-09 21:11:48.000000000 +0000
+++ ../drupal-6.2-patched/modules/path/path.module      2008-05-13 15:45:46.000000000 +0000
@@ -122,6 +122,7 @@ function path_set_alias($path = NULL, $a
     }
   }
   drupal_clear_path_cache();
+  cache_clear_all(NULL, 'cache_path');
 }
 
 
Only in ../drupal-6.2-patched/modules/path: path.module.orig