I see in https://github.com/jupiterjs/jquerymx/blob/master/model/list/list.js that _changed is set on a push and that get() checks changed to determine when to call _makdata. However, I don't see where _changed is ever set back to false. I imagine you'd want to set _changed back to false at the end of _makedata.
I have a list that once populated is pretty static. I populate it by pushing the model instances and today found that it was calling _makedata repeatedly when I am calling get().