Circuits,
I have made the trip from Austin to Wyoming many times and the fastest route that I have found is very similar to what you are doing. If you are leaving from Colorado Springs, go east to Kit Carson, south on 287 to Amarillo/Lubbock, hit 84 to I10, east on I10 and get off (south)to go to Stephenville on 108 or maybe 281. From Stephenville it is about 30 miles east. Unless you just want to drive through Ft. Worth I would avoid it, there is no advantage to do so.
All the Texas roads are good enough to drive fast and you should have no problems with lights (or traffic) until you get off I10.
PS: I have not found anywhere along this route between Kit Carson (I usually am going further north to Limon) and Amarillo that is good to eat, so plan accordingly.