Hello Rahul2011,
A big clue to me in your inquiry is that this is a large form, which also means large views in the form, as well as lots of data. I did a webinar yesterday talking about performance in the browser, and I've seen similar behavior in a form with a view that was too long.
Here is a link to the webinar: https://www.youtube.com/watch?v=Tky6xPHw9CM&list=PL581899A129522F53
In a similar scenario I was able to use paging to hide some of the data in the view, and allow the form to load without issues. Here's a link to a how-to Patrick did a while back: http://www.infopathdev.com/files/folders/examples/entry91133.aspx
Let me know if that helps!
Bre
Bre Huston | Project Manager
Qdabra® Software / InfoPathDev.com / FormsQuo /
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