diff --git a/bundles/groupware/docs/PERFORMANCE b/bundles/groupware/docs/PERFORMANCE
index 9a28fc486ab..666df30e7a4 100644
--- a/bundles/groupware/docs/PERFORMANCE
+++ b/bundles/groupware/docs/PERFORMANCE
@@ -91,6 +91,9 @@ Webserver/PHP tuning
 * Disable DNS lookups in your Apache logging, or use a caching DNS server on
   the web server host.
 
+  Horde itself will run DNS queries too, so make sure your DNS resolution works
+  correctly and fast.
+
 * Enable Apache keepalives.
 
 * You can configure Horde to serve all images, style sheets and/or static
diff --git a/bundles/webmail/docs/PERFORMANCE b/bundles/webmail/docs/PERFORMANCE
index 008f4742c39..98002dbe774 100644
--- a/bundles/webmail/docs/PERFORMANCE
+++ b/bundles/webmail/docs/PERFORMANCE
@@ -93,6 +93,9 @@ Webserver/PHP tuning
 * Disable DNS lookups in your Apache logging, or use a caching DNS server on
   the web server host.
 
+  Horde itself will run DNS queries too, so make sure your DNS resolution works
+  correctly and fast.
+
 * Enable Apache keepalives.
 
 * You can configure Horde to serve all images, style sheets and/or static