Hi, I use the options that resends the data to an url once filled a form. I have found that what happens when sending a form from mobile is:
mobile sends data to formhub server
formhub sends data to my server
my server processes the form and then responds to formhub server
the formhub server responds to the mobile that all is ok
so if the process in my server is very slow it can makes a timeout in the mobile app.
I think that it would be better to divide the formhub operation in two phases, respond to mobile so mobile ends without timeout and after send the data to the url stablished in the options. Although some can say that this is more secure to stablish that all the operation is ok.