diff --git a/TODO.md b/TODO.md
index ab7c245..b554943 100644
--- a/TODO.md
+++ b/TODO.md
@@ -1,5 +1,9 @@
 # TODO
 
+# General
+* Profile guided optimization could be interesting:
+  https://doc.rust-lang.org/rustc/profile-guided-optimization.html
+
 ## aquatic_ws
 * tests
 * ipv4 and ipv6 state split: think about this more..