Why would my heat pump take a long time to heat my house

Heat pumps do not work well when the temperature gets below about 35 degrees. Usually there is another heat source that takes over when the heat pump fails to keep the house warm. Electric is the usual source but gas and oil are also used. Now I am not saying that your heat pump is working good since I am not there to test it so if you feel the heat pump is not working up to its maximum capacity then you should call for On Site service and have it checked out.

What is your second /backup heat/type furnace,, maybe its not doing its part of the job