Improve dashboard performance

Dashboard widgets should defer their data requesting using AJAX so they don't kill/lag the whole page request

modules/backend/controllers/Index.php

@@ -37,13 +37,19 @@ class Index extends Controller
 
     public function index()
     {
-        if ($redirect = $this->checkPermissionRedirect())
+        if ($redirect = $this->checkPermissionRedirect()) {
             return $redirect;
+        }
 
         $this->pageTitle = 'backend::lang.dashboard.menu_label';
         BackendMenu::setContextMainMenu('dashboard');
     }
 
+    public function index_onInitReportContainer()
+    {
+        return ['#dashReportContainer' => $this->widget->reportContainer->render()];
+    }
+
     /**
      * Custom permissions check that will redirect to the next
      * available menu item, if permission to this page is denied.

modules/backend/controllers/index/index.htm

@@ -1,5 +1,21 @@
 <?= $this->makePartial('warnings') ?>
 
 <?= Form::open() ?>
-    <?= $this->widget->reportContainer->render() ?>
+    <div id="dashReportContainer">
+
+        <!-- Loading -->
+        <div class="loading-indicator-container">
+            <div class="loading-indicator">
+                <span></span>
+                <div>Loading dashboard...</div>
+            </div>
+        </div>
+
+    </div>
 <?= Form::close() ?>
+
+<script>
+    $(document).ready(function() {
+        $.request('onInitReportContainer')
+    })
+</script>