Insert check if sharedTemplateGroupID already set

Author: Cyperghost

wcfsetup/install/files/lib/system/template/TemplateEngine.class.php

@@ -1044,17 +1044,19 @@ protected function getCompileFilePrefix(string $templateName): string
 
     private function getSharedTemplateGroupID(): int
     {
-        $templateGroup = \array_find(
-            TemplateGroupCacheBuilder::getInstance()->getData(),
-            static fn (TemplateGroup $group) => $group->templateGroupFolderName === '_wcf_shared/'
-        );
+        if (!isset($this->sharedTemplateGroupID)) {
+            $templateGroup = \array_find(
+                TemplateGroupCacheBuilder::getInstance()->getData(),
+                static fn(TemplateGroup $group) => $group->templateGroupFolderName === '_wcf_shared/'
+            );
+
+            if ($templateGroup === null) {
+                throw new \RuntimeException('Shared template group not found');
+            }
 
-        if ($templateGroup === null) {
-            throw new \RuntimeException('Shared template group not found');
+            $this->sharedTemplateGroupID = $templateGroup->templateGroupID;
         }
 
-        $this->sharedTemplateGroupID = $templateGroup->templateGroupID;
-
         return $this->sharedTemplateGroupID;
     }
 }