Yes some of the maps are more demanding than others. Select lowest graphics quality for best performance, that will simplify the trees. Also, one of the best ways to get better framerate is to run the simulator at lower resolution. You do that by adding command line parameters to the exe file as described in the user manual.
For example:
-screen-fullscreen 0 -screen-width 800 -screen-height 400
(That will run the simulator in a 800x400 window)
As for the buttons it is possible to do already though with a bit of workaround, you can map the keyboard shortcuts to controller buttons with a program such as this:
Windows: http://joytokey.net/en/
Mac: http://alternativeto.net/software/joytokey/?platform=mac
Linux,Windows: https://github.com/AntiMicro/antimicro
Thank you for the feedback!
In FPV Freerider Recharged there is an option for video interference.