btw, do dynamically compiled objects have any disadvantage compared to static objects ?
In desktop jPCT: yes! They are a whole lot slower than static objects. In desktop jPCT, static objects are compiled to display lists using indexed geometry, dynamic ones to vertex arrays using non-indexed geometry by default.
In AE, it depends...! Static objects are compiled to either vertex arrays or VBOs (depending on the setting in Config) using non-indexed geometry, dynamic objects are compiled to vertex arrays using indexed geometry. The behaviour of AE is solely based on the performance characteristics of my phone (and the emulator), i.e. non-indexed geometry is prefered over indexed for static objects, because it's faster (should actually be the other way round like on the desktop, but it's not...). Dynamic objects use indexed geometry, because it decreases update time more than it hurts render time. VBOs are not used for dynamic objects, because it simply doesn't work in my phone that way. However, the difference between vertex arrays and VBOs as well as between indexed and non-indexed geometry on Android is pretty small. VBOs do speed up rendering on modern phones (like N1 or Galaxy S) by around 5-15%...nothing to get crazy about. It doesn't do anything for last generation chipsets like mine.