AppleScript System Events Slowness

In Timeature, I have the app tell Aperture to switch to the Library via AppleScript. What should be a very fast operation turns out to be glacially slow. Any AppleScript wizards care to explain why this is the case? Here’s offending code that you can run in Script Editor:

tell application “System Events”
try
set gLibraryRow to a reference to item 1 of every row of outline 1 of scroll area 1 of splitter group 1 of splitter group 1 of window “Aperture” of application process “Aperture”

select gLibraryRow
end try
end

The script tells Aperture to select the Library row in the Projects Pane. Getting a reference to the library row takes no time at all. It’s the select operation which takes something on the order of 30-60 seconds to complete.