Logitech Unifying receiver lag

I was using my wireless Logitech desktop set but I noticed some lag after not using it for some seconds. When I keep using the mouse or keyboard there is no problem and everything works fine. But when I stop typing or stop mousing for longer than three seconds, the tablet doesn't recognize any input anymore. When I move the mouse or use the keyboard, nothing happens, but after two seconds any input is recognized again.

So I have to keep typing or else I have to wait some seconds to let the tablet recognize any input. This is unworkable.

I tested it with two desktop sets with two different Unifying receivers. When I use a corded mouse or keyboard, everything's fine. It seems to me that there is some sort of logitech standby mode which the tablet can't handle or something.

What can I do abaout this?