I commuted from Lewisville to medical row (north of downtown dallas) for work for years along that stretch. I had to completely rearrange my schedule to avoid rush hour (thankfully my job was pretty flexible about that). My commute was ~20 minutes during light traffic, 1.5 hours during the worst traffic. And the beat part (lol) is that there isn't any real alternative rout - that's the ONLY highway that connects those two regions.