I ran into an issue with increased build times, which were caused by a (seemingly undocumented?) change the default behavior of the UBAExecutor.
By manually disabling it resolves it, so it’s the same as in 5.5, but might be good to include it somewhere in the notes. (maybe it is and I missed it, but I couldn’t find it)
Thread: Build time increased ~10x when migrating from 5.5 to 5.6 - #4 by BartyTurbo1