diff --git a/docs/devnotes.md b/docs/devnotes.md
index e9e1014a..ad3ad483 100644
--- a/docs/devnotes.md
+++ b/docs/devnotes.md
@@ -258,6 +258,7 @@ then build the sfx using any of the following examples:
 
 ```sh
 ./scripts/make-sfx.sh           # regular edition
+./scripts/make-sfx.sh fast      # build faster (worse js/css compression)
 ./scripts/make-sfx.sh gz no-cm  # gzip-compressed + no fancy markdown editor
 ```
 
diff --git a/scripts/make-sfx.sh b/scripts/make-sfx.sh
index c5f8d4f4..44927c15 100755
--- a/scripts/make-sfx.sh
+++ b/scripts/make-sfx.sh
@@ -6,6 +6,8 @@ help() { exec cat <<'EOF'
 
 # optional args:
 #
+# `fast` builds faster, with cheaper js/css compression
+#
 # `clean` uses files from git (everything except web/deps),
 #   so local changes won't affect the produced sfx
 #