diff --git a/news/244.internal b/news/244.internal
new file mode 100644
index 00000000..4fea9be5
--- /dev/null
+++ b/news/244.internal
@@ -0,0 +1,2 @@
+Minor optimization to disable Diazo theming via `X-Theme-Disabled` a tick earlier.
+[thet]
diff --git a/src/plone/app/theming/policy.py b/src/plone/app/theming/policy.py
index d837ff22..227b7b4d 100644
--- a/src/plone/app/theming/policy.py
+++ b/src/plone/app/theming/policy.py
@@ -67,14 +67,14 @@ def getCurrentTheme(self):
     def isThemeEnabled(self, settings=None):
         """Whether theming is enabled."""
 
-        # Resolve debug_mode late (i.e. not on import time) since it may
-        # be set during import or test setup time
-        debug_mode = getConfiguration().debug_mode
-
         # Disable theming if the response sets a header
         if self.request.response.getHeader("X-Theme-Disabled"):
             return False
 
+        # Resolve debug_mode late (i.e. not on import time) since it may
+        # be set during import or test setup time
+        debug_mode = getConfiguration().debug_mode
+
         # Check for diazo.off request parameter
         true_vals = ("1", "y", "yes", "t", "true")
         if debug_mode and self.request.get("diazo.off", "").lower() in true_vals: