Wired doorbells have a transformer which is always on and always using electricity. This is yet one more thing in the house which does this like TV, microwave, remote control things, things with clocks, plug-in phones, etc.
These things add up...
I replaced/rewired my switch so the transformer is only on when the doorbell button is pressed! Thus the transformer is off most of the time now.
I installed a regular electrical box at my front door, ran 14 ga. romex from this box to the doorbell transformer, then got a nice brass blank wall plate, drilled a hole in this plate, then installed a 120V momentary push switch in the plate. Then wired this to switch on the transformer when the button is pressed. Then connected the two wires which were going to the old button so the doorbell would ring as soon as it receives power from the transformer.