I've got about 5fps less than before (roundabout 10-15 fps)... actually, I was quite glad with my result before (20 fps, quite stable). Stuttering definetly increased (especially over towns, but water now stutters too), all tests made in exact same conditions, conf.ini also unchanged, low flying (didn't test high altitudes yet), with trees enabled (low).
I believe this is caused by my GPU (Laptop) - further testing now
My specs: Laptop, 4gb RAM, HD5650 1gb, i5-540M @ 2,53 GHz, Win7 HP
By the way - Game is AWESOME