Glad to hear it's smooth now :)
Well, yes, I think the forest is definitely the most demanding scene. You could try running it at a lower resolution in order to get higher framerate. (You can set the resolution by using command line parameters as described in the manual).
There shouldn't be any noticeable delay on the stick input. Do you notice a delay when looking at the circles on the trim settings screen too? (You can access it directly by clicking "calibrate controller" and then "skip to trim settings").