diff --git a/VERSIONS_WIP/133420 b/VERSIONS_WIP/133420
new file mode 100644
index 0000000000000000000000000000000000000000..0796cb3d6e0910108f081351365210a7ecd25fb4
--- /dev/null
+++ b/VERSIONS_WIP/133420
@@ -0,0 +1 @@
+ - ticket #133420 : Performances de rendu : chargement JQuery UI et Leaflet différés
\ No newline at end of file
diff --git a/library/Class/ScriptLoader.php b/library/Class/ScriptLoader.php
index 59274ea4b3608f2ae784e0cf56a0a954c1619140..ac39dad06aa93b21c7e192d3c7ac3081e6d340f0 100644
--- a/library/Class/ScriptLoader.php
+++ b/library/Class/ScriptLoader.php
@@ -161,10 +161,10 @@ class Class_ScriptLoader {
    */
   public function loadLeafletJS() {
     return $this
-      ->addAdminScript('leaflet-1.6.0/leaflet.js')
+      ->addAdminScript('leaflet-1.6.0/leaflet.js', true)
       ->addJQueryReady('L.Icon.Default.imagePath="' . URL_ADMIN_JS .  'leaflet-1.6.0/images/"')
-      ->addOPACPluginScript('leaflet-ajax-gh-pages/dist/leaflet.ajax.min.js')
-      ->addOPACPluginScript('leaflet.fullscreen-master/Leaflet.fullscreen.min.js')
+      ->addOPACPluginScript('leaflet-ajax-gh-pages/dist/leaflet.ajax.min.js', true)
+      ->addOPACPluginScript('leaflet.fullscreen-master/Leaflet.fullscreen.min.js', true)
       ->addOPACPluginStyleSheet('leaflet.fullscreen-master/leaflet.fullscreen.css')
       ->addStyleSheet(URL_ADMIN_JS . 'leaflet-1.6.0/leaflet.css');
   }
@@ -211,7 +211,7 @@ class Class_ScriptLoader {
       return $this;
 
     return $this
-      ->addScript(JQUERYUI)
+      ->addScript(JQUERYUI, true)
       ->addStyleSheet(JQUERYUI_CSS);
   }
 
@@ -283,8 +283,8 @@ class Class_ScriptLoader {
   /**
    * @return ScriptLoader
    */
-  public function addOPACPluginScript($script) {
-    return $this->addScript(BASE_URL."/public/opac/java/".$script);
+  public function addOPACPluginScript($script, $defer = false) {
+    return $this->addScript(BASE_URL."/public/opac/java/".$script, $defer);
   }
 
 
diff --git a/tests/library/Class/ScriptLoaderTest.php b/tests/library/Class/ScriptLoaderTest.php
index d2f6d457e9fbb6069fa773c685824c90ac9acba3..9d9896307e3d86c3deb8137a9637959010d4ea40 100644
--- a/tests/library/Class/ScriptLoaderTest.php
+++ b/tests/library/Class/ScriptLoaderTest.php
@@ -131,6 +131,7 @@ class ScriptLoaderJsAndCssTest extends PHPUnit_Framework_TestCase {
       ->addScript('opac/cycle.min')
       ->addScript('opac/slides.min.js')
       ->addJQueryReady('alert()')
+      ->loadJQueryUI()
       ->html();
   }
 
@@ -191,6 +192,13 @@ class ScriptLoaderJsAndCssTest extends PHPUnit_Framework_TestCase {
   }
 
 
+  /** @test */
+  public function jqueryUIShouldBeDeferred() {
+    $this->assertContains(JQUERYUI.'?v='.Class_ScriptLoader::getInstance()->getCacheHash().'" defer >',
+                          $this->html);
+  }
+
+
   /** @test */
   function inAjaxModeReadyScriptsShouldBeInSetTimeoutFunction() {
     $this->html = Class_ScriptLoader::getInstance()->beAjax()->html();
@@ -277,4 +285,4 @@ class ScriptLoaderNotificationsBarTest extends ModelTestCase {
   }
 }
 
-?>
\ No newline at end of file
+?>