diff --git a/TODO.md b/TODO.md
index 7a629328e..b16c37b8d 100644
--- a/TODO.md
+++ b/TODO.md
@@ -12,6 +12,7 @@ Performance:
   screen data structure.
 * Screen cell structure should be rethought to use some data oriented design,
   also bring it closer to GPU cells, perhaps.
+* Cache text shaping results and only invalidate if the line becomes dirty.
 
 Correctness: