In test: "sleep time" becomes "page load time"

test/header.html

@@ -62,7 +62,7 @@ form input[type="number"] {
     <input name="whitelist" type="checkbox" :checked_whitelist>
   </label>
   <label>
-    Sleep time:
+    Page load time:
     <input name="sleep" type="number" :value_sleep>
   </label>
   <label>