Bitcomet slowes down when the program window is focused on

Not always, but sometimes it happens that the program slowes down if the program window is focused on, but when you click another window and the program goes in the background, or it is minimized to an icon, the speed goes back to the maximum value.

I tried many times, so I can be sure that it is not just a subjective impression.

The version of software is 1.34 64 bit and the O.S. is Windows Seven 64 bit Ultimate.

Thanks.