(Answering since it's quiet)
I'm not sure this is the best forum for your question if it is about how to write the best possible web application, but there is always an interest in making Chromium (and thus the Chromium based browsers) as fast and efficient as possible. So the question becomes whether Chromium is doing something wrong. For instance if you can run the same application in other browsers and it works better, you should file a performance bug.
Or is it a request to make something faster? Then it probably helps if you pin down exactly what should be faster, and maybe again file a bug for it.
As for what ends up in separate processes, it's easier to say what doesn't. Documents that have, or could get, internal access to each other because they are in the same tab and are loaded from the same domain. They have to be in the same process for Chromium to get all the (potential) javascript execution right.
/Daniel