update TODO.md

TODO.md

@@ -1,9 +1,6 @@
 Performance:
 
-- for scrollback, investigate using segmented list for sufficiently large
-  scrollback scenarios.
 - Loading fonts on startups should probably happen in multiple threads
-- `deleteLines` is very, very slow which makes scroll region benchmarks terrible
 
 Correctness:
 
@@ -15,10 +12,6 @@ Correctness:
   - can effect a crash using `vttest` menu `3 10` since it tries to parse
     ASCII as UTF-8.
 
-Improvements:
-
-- scrollback: configurable
-
 Mac:
 
 - Preferences window
@@ -27,3 +20,10 @@ Major Features:
 
 - Bell
 - Sixels: https://saitoha.github.io/libsixel/
+
+paged-terminal branch:
+
+- tests and logic for overflowing page capacities:
+  * graphemes
+  * styles
+- configurable scrollback size