Yes, I'm using DX11 (it's just like 10, basically). Doesn't your HD 3870 support DX10? It should generally be better. Try using it.
I wasn't intending it to be a flat-out example of how to set yours, just showing you what it looked like, ya know?
(Also, the hacks on the bottom are something you can enable in the gsdx.ini)
You can also now increase the
EE Cyclerate and/or
VU Cycle Stealing Speedhacks. These can give better performance, but can also cause problems. How much of which one (or both) will be too much will vary between games (some will benefit greatly, others may break quickly). Try and see what works best for you, and see what's "too much" (if new problems occur). I'd suggest starting with the
EE Cyclerate for this one.
BTW - Be sure and read the stickies. Much of this is covered.