Now you see, it seems to have improved my Mac... Even though its been perhaps diagnosed as a hardware fault for mine. I don't get any hangs or that poxy SBBOD. But time will tell for me.
I had same issue on my MBP but after 15 minutes it just restarted itself and now runs as should I bet they do some post install steps when rebooting thats why - and depending on CPU and RAM it probably takes around 10-30 minutes.