I was wondering which ext package to use as a minimum, while native components would be dynamically loaded as needed. I used the forum example. Here are my findings:
Doesn't work for core components (e.g. Element.js). Location for Element.js is src/core/src/dom/Element.js, but Loader expects src/core/Element.js
works, but then your client loads a bunch of files after the first component initialization
I guess dynamic loading is best used for widgets built for particular app, not for native Ext JS 4 components. Otherwise, it might be a good idea to use jsbuilder for a custom Ext JS 4 build and load anything further on top of that.
Please report your experiences.