The 560ti is a bit slower than Hitech's GTX 660 card, but you are further handicapped with only 1GB of dedicated video RAM.
A couple of simple tweaks should get you some frame rate back.
In Video Settings:
Make sure the "Maximum Texture Size" is 2048. or less.
In then game under Options->Graphic Details
Make sure the "Environment Map" slider is set to None.
Check "Disable Post Lighting" and "Disable Shadows"
See what that does for you. Play with the options until you get the frame rate you want.
All that said, keep in mind the current Beta 13 release does have a video card memory issue which is causing a lot more memory to be used than it should be.