Hi DevilCat and welcome to Chordie,
I assume that you are playing D using your index, middle and ring fingers. Some of my students find it easier to use the index finger to barre the first three (G, B and e) strings on the second fret and then use the middle finger to play the second (B) string on the third fret. This way you are only having to postion two fingers.
At then end of the day though it is only through repetition that changes become easy and of course that means practice, practice and then even more practice. What you are doing with practice is training your muscles and tendons in your fingers to automatically lock into a certain configuration to form each chord, there is no easy shortcut to this I'm afraid.
Good luck,
Roger