@mdamson, that sounds like your hitting the wall with the performance of your graphics card, which is why turning off excess graphics features restores functionality.
With respect to @Johnson_BigMatt 's problem, I honestly wonder if this is a Solid Edge issue or a larger Windows 10 issue.
The perceived feeling of ST9 compared to ST8 it is an overall loss of performance.
Looking at all the complain about ST9 should raise the attention on what's happened.
In my everyday workstation I still have Windows 7, so there must be something in ST9 too and not just on Windows 10.