Coding a better flex mobile app

[Gabriele Campi [Media Logic]]

Hi,

last year I created a mobile app for IOS and Android using Apache Flex.
My app uses a SQLite database and makes large use of graphics and 
bitmapdata (being a design app that manipulates images) and I 
encountered many problems with general performances and memory 
management. My app now is heavy and slow.
It was my first project with Flex and Air technologies, and now it's 
time to clear, improve, rewrite the code. What would be the better approach?

Just to test performances I created an Hello World app in Objective-C, 
AS3 and Flex, just a pair of views with a few buttons, and the Flex one 
was dramatically slow and heavy compared with the others.

There are many opportunity out there (MVC frameworks like Robotlegs and 
PureMVC, or pure AS3 solutions like MadComponents), could they be a 
viable alternative?

Thanks

Gabriele