My biggest concern about ExtJS is it's size. I realized that extjs-all is huge and i'd like to help on that. All I use ATM are form fields, data stores and button. That's all I have on my ExtJS application. For that it would be silly to load all the rest of the components, but I have no idea how to create a smaller build that suits my application better.
I'd be happy if you pointed me into the right direction.