I've been running the same installation of CB for a couple of months. In the past couple of days it has just started hanging completely - taking 99% of CPU and not responding very well (it does occassionally respond but it's largely hung up).
I noticed that CB was hung up badly yesterday and that it had a notice about an upgrade. I upgraded and the hang seems even worse now - it basically hangs when it starts now. On occasion I can get it to start up and serve out a few Captchas but it tanks out within minutes.
It's on a dedicated (and clean) Windows 2012 Server box.