Update README.md

phannhat17 · web-flow · commit ee3e14ee148b · 2025-09-15T00:42:35.000+07:00
diff --git a/README.md b/README.md
@@ -21,6 +21,9 @@
 
 ---
 
+> [!WARNING]
+> The current cheating-detection algorithm is very slow, so it is NOT recommended for competitions with many participants.
+
 ## Getting Started
 
 This section provides instructions for setting up the project locally.
