I dont't really know a cross browser method for multiple requests besides AJAX... Websockets are there to help this out but it's almost experimental.
But there is also how informations are accessibles into the webserver to take care about. The most common option is to use a database ton store users informations but this not often the best choice, first of all because it's implicate more network traffic (between the database and webserver).
An other option is to check about SOAP services for sharing objects. Maybe the among of data between webserver and client is higher but the servers communication is simplified.
Of course this option is usefull when database and webserver are not on the same physical machine...
That's just an idea