The developer I work with had a pertinent idea/question. I'm not much into programming so i'll try my best to explain the point. He said to me that when you have only one effect for a given component transition, let's say I aplied fade effect, that effect shouldn't be inserted in a "parallel" (as seen in Flex) since it parallels to nothing else.
another thing he said was that when you have the same effect applied to multiple components (main buttons fading in whenever), Flex should create (in the code) only one effect with multiple targets instead of creating multile effects to one target as it does now
I hope you guys understood me. If you have any questions please comment.
Your developer is right - Catalyst generates transitions code that's not as compact as it could be. He should feel free to optimize the code. However, it might not be worth doing unless you're noticing a performance problem on your site.
In general, the code that Catalyst generates may not be as efficient as code that can be hand-coded. This is virtually always the case with high-level programming (you can always write assembly code that's more efficient than the assembly that your C compiler creates), but we will work to make the code FC generates simpler and more efficient over time.