diff --git a/docs/docs/codebase/setup/config.md b/docs/docs/codebase/setup/config.md
index e8f263f9b..40ad156ec 100644
--- a/docs/docs/codebase/setup/config.md
+++ b/docs/docs/codebase/setup/config.md
@@ -113,6 +113,21 @@ We use an ARC session token in order to pull scores from `ARC`. The session toke
 and profile pictures. This is a folder somewhere on the
 system (presumably using nginx serve-static).
 
+### CDN_URL
+
+- Type: URL or null (Optional).
+
+This parameter dictates where the CDN server is. Requests that hit the CDN
+will be redirected here. If null, or not present, `tachi-server` will use
+filesystem calls for the files (and return them) instead of redirects.
+
+!!! note
+	Nginx Serve-Static is relatively easy to set up, and provides
+	massive performance increases for this kind of stufff.
+
+	I highly recommend against leaving this null, as you can cause
+	large performance deficits.
+
 ### PORT
 
 - Type: Port (1-65536)