A few more updates (which I also posted in the beta patch thread). The lockup occurs not just when exiting a battle, but can also happens when exiting the trade screen, exiting a town, etc. I did some more testing with the release and the beta branches while monitoring the temperature of my GPU, and I think I found a correlation.
What I'm having problems with is my laptop (no issues on my desktop, btw). The laptop has a Nvidia Quadro M1200 as a GPU. Monitoring the temp with the release branch, and it remains in the low to mid 80s (82C - 86C). With the beta branch, the temp would rise rapidly above 90C, and that's when the lockup would happen.
So I turned vsync on, and with the release branch, the temp stabilized around 82C. With the beta branch and vsync on, the temp would spike above 90C for a moment right after the game loaded, and then would fluctuate between 83C - 86C.
So turning vsync on did allow me to use the beta branch on my laptop, but this issue did not exist prior to Friday's patch.