diff --git a/applications/butler/templates/ingress-authenticated.yaml b/applications/butler/templates/ingress-authenticated.yaml
index bf7127de6e..d20e8bc8a2 100644
--- a/applications/butler/templates/ingress-authenticated.yaml
+++ b/applications/butler/templates/ingress-authenticated.yaml
@@ -5,6 +5,9 @@ metadata:
   labels:
     {{- include "butler.labels" . | nindent 4 }}
 config:
+  # The Butler server often services large numbers of small requests,
+  # so this cache reduces the load on Gafaelfawr.
+  authCacheDuration: 5m
   baseUrl: {{ .Values.global.baseUrl | quote }}
   scopes:
     all: