When the schema browser is in treeview, if I select a procedure on the left side, to display the source code, the RHS flickers (the horizontal scroll bar) and the cursor flickers the SQL cursor image several times and it takes a while to display the code in the source tab. When in other views, the code displays right away and does not flicker.
WORKAROUND:
Use a view other than treeview.
STATUS:
Waiting for fix to be included in a future release of Toad for Oracle.