Flash Remoting connection performance

I am building an application where I do not need to be regularly connected  
to the server, but periodically, say every five minutes, I need to connect and  
get an update.
 
My question is, does remoting create a persistent connection to the server  
until you disconnect. If so how expensive are these connection calls.
 
I need a very lightweight way of being able to connect to a server, get  some 
status information, and get out. And I need to allow lots of machines,  
perhaps hundreds of thousands, to check in periodically, so I don't think I  can 
afford to leave open a bunch of tcp/ip connections for the server to  maintain.
 
Any insight into the best way to do this, and if flash remoting will work  
for this strategy would be greatly appreciated.
 
Hank