After reading up on antialiasing, I have read that SSAA (Super Sample Anti Aliasing) is a brute force method which gives the best quality, but at a huge performance hit.

MSAA (Multi Sample Anti Aliasing) is an optimisation of SSAA. It is computationally much less intensive and gives almost as good results.

FXAA (Fast Approximate Anti Aliasing) is done in post processing. It operates on the raster image rather than the scene geometry. It is inferior to MSAA but almost free computationally.

Train Simulator does not have any options without FXAA. On Bradgamer, I am trying FXAA + 8 X MSAA. It leaves a bit of moire, but I'm getting good frame rates.

I have limited the frame rate in Train Simulator to 60FPS using the command line switch:

-FPSLimit=60