What does "Reactivity" do in the controller settings?

I thought reactivity adjustment sounded great when I discovered it and reduced it to 65 percent to smooth out my flying a little. It seemed to work, then after a couple of days flying CE208, I realized the power lever wasn’t reducing power all the way and I wasn’t able to get the plane to settle on the runway. The Caravan in SIM is tricky this way anyway. So, I changed the reactivity back to 100, and boom, I can land again . Anyone else?