Hi everyone,
I had also problems with my storyline in Final Cut Pro X with hanging/freezing when I wanted to play from stroyline.
I'm not sure if this is really a driver issue.
I recognized in "Activity monitor" in "Harddisk" section while Final Cut Pro X freezes that FCPX was reading a mass of data (10gb-15gb every freeze). After waiting a time, FCP X was again working and I could edit and play in FCPX.
So I'm not sure if that problem is driver or FCPX related but it seems like that during the hanging process, FCPX is reading datas in background. I have no optimized or proxy media and after working 3 hours in FCPX, reading was about 80gb.
The most jumps (increasing for reading data) were when FCPX was hanging.
So I don't know what exactly the problem is but for now, its working for me.
I have a Skylake system with GTX980Ti (latest Web driver installed) and installed macOS Sierra.
EDIT:
During freeze, I killed Nvidia process in activity monitor.