Web User State Management and Serialization

Hello,

I am currently playing with RoR and I wanted to get State Management
in. If a user just shuts the browser down and starts it up again (+
logs in), there should be anything back on the screen (anything that
was there when the last response from the server arrived).

Is it a good Idea to use rubys Marshal.dump + Marshal.load [1] and
then store the dumped thing somewhere? What about performance?

A user invokes an ajax action, a response is being generated - this
happens very often - each time the “system” will mashal some instances.

Whats your thoughts about this?

[1] Serialization - Wikipedia