A K-1 might be a bit faster bit not by much. The only other option is get a work visa (such as an O-1 or L-1) and then when you are in the U.S., file your marriage-based green card application, which in most instances is taking less than 6 months. The immigrant visa process, as you correctly note, is taking a while, anywhere from 12 to 18 months, depending on the Consulate.