diff --git a/TODO b/TODO
index 2859895a..212c7233 100644
--- a/TODO
+++ b/TODO
@@ -23,6 +23,8 @@ verbose mode, which usage for the library log callback, debug levels, ...)
 
 - add .lastupdate files support for "files" db downloads
 
+- review .lastupdate implementation: is the .lastupdate file really needed?
+
 
 ADDITIONAL IDEAS FOR PERFORMANCE IMPROVEMENT
 ============================================
@@ -32,3 +34,5 @@ that basically contains the output of `ls -1 /var/lib/pacman/{repo}`.  This
 cache file could be used in -Q and -Si/s operations to speed up package
 listings.
 
+- move the cache structure to a binary balanced tree instead of a double 
+chained list