diff --git a/admin/tool/customlang/locallib.php b/admin/tool/customlang/locallib.php
index acdeb5356e7..2e5df0e84e7 100644
--- a/admin/tool/customlang/locallib.php
+++ b/admin/tool/customlang/locallib.php
@@ -36,7 +36,7 @@ class tool_customlang_utils {
      * Rough number of strings that are being processed during a full checkout.
      * This is used to estimate the progress of the checkout.
      */
-    const ROUGH_NUMBER_OF_STRINGS = 16500;
+    const ROUGH_NUMBER_OF_STRINGS = 30000;
 
     /** @var array cache of {@link self::list_components()} results */
     private static $components = null;
@@ -91,9 +91,22 @@ class tool_customlang_utils {
     public static function checkout($lang, progress_bar $progressbar = null) {
         global $DB;
 
+        // For behat executions we are going to load only a few components in the
+        // language customisation structures. Using the whole "en" langpack is
+        // too much slow (leads to Selenium 30s timeouts, especially on slow
+        // environments) and we don't really need the whole thing for tests. So,
+        // apart from escaping from the timeouts, we are also saving some good minutes
+        // in tests. See MDL-70014 and linked issues for more info.
+        $behatneeded = ['core', 'core_langconfig', 'tool_customlang'];
+
         // make sure that all components are registered
         $current = $DB->get_records('tool_customlang_components', null, 'name', 'name,version,id');
         foreach (self::list_components() as $component) {
+            // Filter out unwanted components when running behat.
+            if (defined('BEHAT_SITE_RUNNING') && !in_array($component, $behatneeded)) {
+                continue;
+            }
+
             if (empty($current[$component])) {
                 $record = new stdclass();
                 $record->name = $component;
@@ -103,7 +116,7 @@ class tool_customlang_utils {
                     $record->version = $version;
                 }
                 $DB->insert_record('tool_customlang_components', $record);
-            } elseif ($version = get_component_version($component)) {
+            } else if ($version = get_component_version($component)) {
                 if (is_null($current[$component]->version) or ($version > $current[$component]->version)) {
                     $DB->set_field('tool_customlang_components', 'version', $version, array('id' => $current[$component]->id));
                 }