Smart.Grid rerenders itself when needed and upon many events. This is the default behaviour and it is not problematic. You are maybe triggering the rerender of it with some non-grid-related code. You may see that even if you open your dropdown in a smaller viewport, the grid will trigger a rerender.
I can see that in your grid_init function, you are invoking the ‘ajaxProgressStop’ method, which may cause this rerender if the method has something to do with the DOM.

Best Regards,
Svetoslav Borislavov

Smart UI Team