A second beta update -- 1.2.37 -- has been released for Fallout 4 owners on Steam. The main change this time is further improvement of memory optimization and stability; you also get better performance inside the Corvega Assembly Plant and a fix for becoming stuck in terminals.
Below are the instructions for accessing the patch. Bethesda advises you to back up your save games before doing any of it, given this is a beta program.
To get the beta, you need to do the following:
1. Log into Steam
2. Right Click on Fallout 4 in your Library
3. Select Settings
4. Select Betas
5. A drop down menu will appear. Select Beta Update
6. Select OK.
7. Wait a few minutes and Fallout 4 should update.
8. When done, Fallout 4 should appear as Fallout 4 [beta] in your Library
If you decide you don't want to run the Beta anymore, redo steps 1 - 4. At the drop down, select NONE - Opt out of all beta programs.