sorting is causing 2 fetchData calls

Hey,

i've got a little problem, while sorting a listgrid with a dataSource.
I've overwritten the sortChanged method, so it will register the new sorting field and direction and send it to my backend.

The backend will sort the data reprensented in the listgrid. After the request is done i'll fetch the data of the listgrid anew.
If i've a lot of data, it happens that the listgrid is fetching the data twice.

If the sortChanged request lasts to long, it seams that the listgrid is fetching the data on it's own.
Is there a way to disable this automatic fetch or at least set some kind of "sortDelay"? As i can see right now there is no way of doing so.

regards
marcus