Teddy Pasternak at 2012-03-14 12:16:02:
The scene is very similar to the script. The biggest difference is the elimination of these lines:
“Looking at her, you might think she was a sweet, innocent teenage girl. But she wasn't sweet. And she wasn't innocent. She was selfish and cynical and ambitious and thought nothing of destroying the lives of others to get to the top.”
That's most likely a choice made in editing as the point gets across anyway. Perhaps Payne and editor Kevin Tent thought it was too much or felt too on-the-nose to spell out exactly what was going through Jim's mind right then. Plus, he says "The sight of Tracy at that moment affected me in a way I can't fully explain."
I think this is a case where less is more and leaving these specifics out makes Jim's reasoning slightly more ambiguous and underscores the “I can't fully explain." line.