Issue #1443308 by cilefen, joseph.olstad, mikeytown2, joelpittet, btopro, alexpott, jonhattan, marcingy, stewsnooze, Fabianx, pounard, tstoeckler, penyaskito: Add static cache to module_load_include()

CHANGELOG.txt

@@ -1,6 +1,7 @@
 
 Drupal 7.42, xxxx-xx-xx (development version)
 -----------------------
+- Added static caching to module_load_include() to improve performance.
 - Fixed double-encoding bugs in select field widgets provided by the Options
   module. The fix deprecates the 'strip_tags' property on option widgets and
   replaces it with a new 'strip_tags_and_unescape' property (minor data

includes/module.inc

@@ -320,16 +320,27 @@ function module_load_install($module) {
  *   The name of the included file, if successful; FALSE otherwise.
  */
 function module_load_include($type, $module, $name = NULL) {
+  static $files = array();
+
   if (!isset($name)) {
     $name = $module;
   }
 
+  $key = $type . ':' . $module . ':' . $name;
+  if (isset($files[$key])) {
+    return $files[$key];
+  }
+
   if (function_exists('drupal_get_path')) {
     $file = DRUPAL_ROOT . '/' . drupal_get_path('module', $module) . "/$name.$type";
     if (is_file($file)) {
       require_once $file;
+      $files[$key] = $file;
       return $file;
     }
+    else {
+      $files[$key] = FALSE;
+    }
   }
   return FALSE;
 }