traffic is horrible during rush hours for both. I suggest you skip the freeways and go "local."
If you're staying near the Arboretum, get on 360 heading South, and then make a left turn on 2222, and just get on Shoalcreek or Lamar, which will take you through neighborhood streets, eventually to UT in a much shorter time than taking the freeway.
Bear in mind the next problem you would have is to find parking near Campus. For one, you cannot drive into campus unless you have a letter stating you have a special visitor's parking permit issued to you. Otherwise you'll either end up hunting for a parking space around 24th street's fraternity row, or have to park so far away that you'd need to take a shuttle to get near campus.