diff --git a/prequeue.py b/prequeue.py
index 991db7eb8..156d3e942 100644
--- a/prequeue.py
+++ b/prequeue.py
@@ -1,3 +1,9 @@
+# coding: utf-8
+
+# Starting a new python process to preprocess each source file
+# creates too much overhead. Instead, a list of files to preprocess
+# is fed into a script run from a single process.
+
 import os
 import sys
 import preprocessor