Tommy: Welcome. Very nice. Speed down the hill is something that I have experienced (with several different engines) in the past. Being a “Christmas” temporary layout, I would not be too concerned. Just enjoy being a “hands-on” engineer and slow the train on the downgrade by using the transformer. (One thing great about a “Christmas” layout is that each year you can add something new…and it does not have to be expensive.) Have a great holiday.
A great start to your Christmas layout. Make sure you use “snow” that is, and I believe this the correct term, flameproof for the safety of all who will enjoy the layout. Watch for after Christmas sales on lighted buildings and if you can find the ones lit with fiber optics, they are awesome.