[pisteoff]

I think this is exactly correct. I've used ExtJS exactly once and it was for building an internal, administrative app.

It's also correct that building an administrative interface with Rails or Django is much easier. In the case of the app I was building we had to interface with some Django code, so I wrote this Python meta-class that would inspect Django models and produce classes that would then produce ExtJS models, widgets, etc. that could then interact RESTful interfaces provided by the Django app. It worked great but was slow due to javascript blocking issues. So like you said performance issues were a barrier, but I doubt in that case it was ExtJS's fault. I've thought about posting that code somewhere but I'm kind of embarrassed that I actually tried it. After that little experiment we scrapped ExtJS and built a strait Django application that did what we needed.