It's hard to convince a team of 100 people that the programmers can't simply "fix" the performance of the engine, and that some of the ways people had gotten used to working to needed to be changed. People needed to understand that the performance of the game was everybody's problem, and I figured the best way to do this is with a bit of humor that had a bit of hidden truth behind it.
The solution took maybe an hour. A fellow programmer took four pictures of my face -- one really happy, one normal, one a bit angry, and one where I am pulling my hair out. I put this image in the corner of the screen, and it was linked to the frame rate. If the game ran at over 30fps, I was really happy, if it ran below 20, I was angry.
After this change, the whole FPS issue transformed from, "Ah, the programmers will fix it." to, "Hmm, if I put this model in, Nick is going to be angry! I'd better optimize this a little first." People could instantly see if a change they made had an impact on the frame rate, and we ended up shipping the game at 30fps.