not even my GTX 670 can run CLoD acceptably?

[FS~Phat]

You might need to turn some settings down..
I did a lot of testing over the last few days and the particle smoke and tracer effects are quite demanding even on my system with everything turned up to maximum with quite a few planes in close proximity.

My normal FPS is 70-90FPS over the channel and when I was doing some bomber intercept practice with 9 bombers my FPS would momentarily drop to 30FPS when lots of smoke or debris were around.

Until some of the code is further optimised your best to turn some effects down.
They dont dramatically change the gameplay or visuals down a notch.
Your CPU is definitely not up to the task for lots of complex models and damage so your only option is to turn down some features.