Welcome Phil. As already mentioned speed and dept of cut make a huge difference. Hardness of wood should be considered as well. Most new router owners who haven't used these tools before make the mistake of trying to make the cut in one pass which for shallow cuts is fine but trying more that 1/8" to 3/16" in one pass is going to be a problem. A video series I watched once had the cutter set for the final depth but the operator had 1/8" hardboard cut so the cutter was clear of the board when laid over. If the depth of cut needed was say 1/2" there would be 4 - 1/8" boards stacked and after each pass he would remove one of those boards. Same difference if you adjust the cutter up after each pass.