First go to ur To-do List.
Make a note and input as follows
Subject: Speed
Due Date: 29-01-2005(dd-mm-yy)
Priority: set to High
then press Done

Go to option again and make a second note and input as follows
Subject: Qoukie
Due Date: 29-01-2005(dd-mm-yy)
Priority: set to Low
then press Done

Do not exit yet. Highlight the Speed note, select Options and Mark as done.
Then highlight the Qoukie note, select Options and Mark as done.
Now, reboot your mobile.

-Anyway in the menu of n73ME there wasn't an icon named to do list.Try to find To-do-List in Calendar\Agenda & proced with the same procedure
i try it and now my phone run more faster.