When deleting un-needed applications, I'm always very careful to do full searches for related files, folders, plists, etc., in order to keep my system clean.
Just recently, I detected a noticeable performance lag accessing contextual menus. A quick peek into the Contextual Menus Items in my /Users -> user_name -> Library folder uncovered a folder for contextual menus left over from a demo of Extensis' Portfolio, which I had recently deleted after the deom expired. A quick disposal of the straggler brought instant performance gains to all contexutal menu accesses. Hope this will be helpful to others experiencing similar problems.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20030603115637226