diff --git a/modules/field/field.module b/modules/field/field.module
index 77b5dde..9cc142b 100644
--- a/modules/field/field.module
+++ b/modules/field/field.module
@@ -425,12 +425,23 @@ function field_modules_disabled($modules) {
 function field_sync_field_status() {
   // Refresh the 'active' and 'storage_active' columns according to the current
   // set of enabled modules.
-  $all_modules = system_rebuild_module_data();
-  $modules = array();
-  foreach ($all_modules as $module_name => $module) {
-    if ($module->status) {
-      $modules[] = $module_name;
-      field_associate_fields($module_name);
+  //
+  // But don't run the full system_rebuild_module_data() during installation,
+  // as it is slow.
+  if (variable_get('install_task') != 'done') {
+    $modules = module_list(TRUE);
+    foreach ($modules as $module) {
+      field_associate_fields($module);
+    }
+  }
+  else {
+    $all_modules = system_rebuild_module_data();
+    $modules = array();
+    foreach ($all_modules as $module_name => $module) {
+      if ($module->status) {
+        $modules[] = $module_name;
+        field_associate_fields($module_name);
+      }
     }
   }
   db_update('field_config')