Fist i want to say this is a awsome product, and now i have some sugestions ( sorry if this is repost , but i didn't found anything regarding this topic )
I'm building some big site dinamic site strucutre where i have somewhere about 14 tabs with around 15 inputs ( textfields) in it. So when i load that page from backend i have kind of shortpipe problems with latency and perfomance.
My sugestion is to put lazy loading on roadmap, porhaps you can se zimbra use case http://www.zimbra.com/blog/archives/2007/03/lazy_loading.html where they found enhacment in about 50% of backend speed.
I will probably solve this on some weird way ( to dinamicly create iframe or something ) but the thing is that this should be a feature