diff --git a/info.xml b/info.xml
index 4b243dd..0b4e38e 100644
--- a/info.xml
+++ b/info.xml
@@ -34,7 +34,7 @@
   </classloader>
   <mixins>
     <mixin>menu-xml@1.0.0</mixin>
-    <mixin>smarty-v2@1.0.1</mixin>
+    <mixin>smarty-v2@1.0.3</mixin>
   </mixins>
   <upgrader>CRM_Outlook365_Upgrader</upgrader>
 </extension>
diff --git a/mixin/smarty-v2@1.0.1.mixin.php b/mixin/smarty-v2@1.0.1.mixin.php
deleted file mode 100644
index 5972dbd..0000000
--- a/mixin/smarty-v2@1.0.1.mixin.php
+++ /dev/null
@@ -1,51 +0,0 @@
-<?php
-
-/**
- * Auto-register "templates/" folder.
- *
- * @mixinName smarty-v2
- * @mixinVersion 1.0.1
- * @since 5.59
- *
- * @param CRM_Extension_MixInfo $mixInfo
- *   On newer deployments, this will be an instance of MixInfo. On older deployments, Civix may polyfill with a work-a-like.
- * @param \CRM_Extension_BootCache $bootCache
- *   On newer deployments, this will be an instance of MixInfo. On older deployments, Civix may polyfill with a work-a-like.
- */
-return function ($mixInfo, $bootCache) {
-  $dir = $mixInfo->getPath('templates');
-  if (!file_exists($dir)) {
-    return;
-  }
-
-  $register = function() use ($dir) {
-    // This implementation has a theoretical edge-case bug on older versions of CiviCRM where a template could
-    // be registered more than once.
-    CRM_Core_Smarty::singleton()->addTemplateDir($dir);
-  };
-
-  // Let's figure out what environment we're in -- so that we know the best way to call $register().
-
-  if (!empty($GLOBALS['_CIVIX_MIXIN_POLYFILL'])) {
-    // Polyfill Loader (v<=5.45): We're already in the middle of firing `hook_config`.
-    if ($mixInfo->isActive()) {
-      $register();
-    }
-    return;
-  }
-
-  if (CRM_Extension_System::singleton()->getManager()->extensionIsBeingInstalledOrEnabled($mixInfo->longName)) {
-    // New Install, Standard Loader: The extension has just been enabled, and we're now setting it up.
-    // System has already booted. New templates may be needed for upcoming installation steps.
-    $register();
-    return;
-  }
-
-  // Typical Pageview, Standard Loader: Defer the actual registration for a moment -- to ensure that Smarty is online.
-  \Civi::dispatcher()->addListener('hook_civicrm_config', function() use ($mixInfo, $register) {
-    if ($mixInfo->isActive()) {
-      $register();
-    }
-  });
-
-};
diff --git a/mixin/smarty-v2@1.0.3.mixin.php b/mixin/smarty-v2@1.0.3.mixin.php
new file mode 100644
index 0000000..f8718c8
--- /dev/null
+++ b/mixin/smarty-v2@1.0.3.mixin.php
@@ -0,0 +1,78 @@
+<?php
+
+/**
+ * Auto-register "templates/" folder.
+ *
+ * @mixinName smarty-v2
+ * @mixinVersion 1.0.3
+ * @since 5.59
+ *
+ * @deprecated - it turns out that the mixin is not version specific so the 'smarty'
+ * mixin is preferred over smarty-v2 (they are the same but not having the version
+ * in the name is less misleading.)
+ *
+ * @param CRM_Extension_MixInfo $mixInfo
+ *   On newer deployments, this will be an instance of MixInfo. On older deployments, Civix may polyfill with a work-a-like.
+ * @param \CRM_Extension_BootCache $bootCache
+ *   On newer deployments, this will be an instance of MixInfo. On older deployments, Civix may polyfill with a work-a-like.
+ */
+return function ($mixInfo, $bootCache) {
+  $dir = $mixInfo->getPath('templates');
+  if (!file_exists($dir)) {
+    return;
+  }
+
+  $register = function($newDirs) {
+    $smarty = CRM_Core_Smarty::singleton();
+    $v2 = isset($smarty->_version) && version_compare($smarty->_version, 3, '<');
+    $templateDirs = (array) ($v2 ? $smarty->template_dir : $smarty->getTemplateDir());
+    $templateDirs = array_merge($newDirs, $templateDirs);
+    $templateDirs = array_unique(array_map(function($v) {
+      $v = str_replace(DIRECTORY_SEPARATOR, '/', $v);
+      $v = rtrim($v, '/') . '/';
+      return $v;
+    }, $templateDirs));
+    if ($v2) {
+      $smarty->template_dir = $templateDirs;
+    }
+    else {
+      $smarty->setTemplateDir($templateDirs);
+    }
+  };
+
+  // Let's figure out what environment we're in -- so that we know the best way to call $register().
+
+  if (!empty($GLOBALS['_CIVIX_MIXIN_POLYFILL'])) {
+    // Polyfill Loader (v<=5.45): We're already in the middle of firing `hook_config`.
+    if ($mixInfo->isActive()) {
+      $register([$dir]);
+    }
+    return;
+  }
+
+  if (CRM_Extension_System::singleton()->getManager()->extensionIsBeingInstalledOrEnabled($mixInfo->longName)) {
+    // New Install, Standard Loader: The extension has just been enabled, and we're now setting it up.
+    // System has already booted. New templates may be needed for upcoming installation steps.
+    $register([$dir]);
+    return;
+  }
+
+  // Typical Pageview, Standard Loader: Defer the actual registration for a moment -- to ensure that Smarty is online.
+  // We need to bundle-up all dirs -- Smarty 3/4/5 is inefficient with processing repeated calls to `getTemplateDir()`+`setTemplateDir()`
+  if (!isset(Civi::$statics[__FILE__]['event'])) {
+    Civi::$statics[__FILE__]['event'] = 'civi.smarty-v2.addPaths.' . md5(__FILE__);
+    Civi::dispatcher()->addListener('hook_civicrm_config', function() use ($register) {
+      $dirs = [];
+      $event = \Civi\Core\Event\GenericHookEvent::create(['dirs' => &$dirs]);
+      Civi::dispatcher()->dispatch(Civi::$statics[__FILE__]['event'], $event);
+      $register($dirs);
+    });
+  }
+
+  Civi::dispatcher()->addListener(Civi::$statics[__FILE__]['event'], function($event) use ($mixInfo, $dir) {
+    if ($mixInfo->isActive()) {
+      array_unshift($event->dirs, $dir);
+    }
+  });
+
+};