Page becomes unresponsive during RPC

Hi Team,

We are currently using:-
BuildDate Wed Mar 05 15:52:00 IST 2014
Version 4.1p
SCVersionNumber v9.1p_2014-03-05

We are using grid component of GWT in our application. Each time a remote procedural call is made to fetch data, the page becomes unresponsive till the data is received. Due to this, the user cannot perform any action till data is received. How can this call be made asynchronous.