glScissor & performance

Yes, I’m aware of that - but getting the value of some of the simpler states used to be light weight with nvidia in XP, until the driver was put in another thread. It’s fair enough, but people should be aware of this increase in cost.
Now I’m just curious about how it all works and what pitfalls to look out for. High jacking a korval thread seemed to be the best way to get answers.