Actually, performance isn't as much an issue as the second one, which is the scope concern. 

I'm still trying to be certain about the scope and thread safety involved. Remember, the reason why Django didn't get CBVs for a long time was because this is a hard problem. Heck, Marty Alchin even got it wrong in 1st edition Pro-Django. You've got a neat idea, I'm just trying to be certain it's safe. And checking for safety in this case isn't easy.  :fallen_leaf: