It is possible that the server runs a backup, but the server is good and the backup not very heavy, so I would not think a server problem. (Even I some reboots can happen).
If the server is gone, the builder do not insist with ajax (timeout). Every 10 seconds, a system ajax 'ping' is done to check the server and to exchange with the session.
I think a javascript bug in the builder.
I often can see when I leave my Builder window opened for few days, then Firefox lacks and blocks with an anormal use of CPU and memory.
This is a testimonial that something is not coded very good in the JS, but since the beginning of the project, I can't find it. So it stays as it is for the moment.
If somebody is experienced to help me understanding the use of the memory and CPU of the browser I am very interrested to make the service evolving.
What you should know, it is nice to restart the builder every 5-8 hours (for my experience), wich is still not too bad.
I experienced the same with some music streaming websites as well (Grouveshark for example), and I was asking myself is heavy applications are supported well in Firefox.
) that put the server on knees...
