Here are a couple screens to show you what I mean:
Taken on the Cajon Pass
I should probably mention my specs:
i3 550 3.2Ghz, 4GB DDR3 RAM, Radeon HD 5770.
This is the first time I used a Radeon card and I am very pleased with it. I experience no more trouble with it than I did when I used nVidia in Railworks.
I have my Railworks settings maxed out except AA which is on 4xMSAA (used to have it on 8x but there is really no difference between 4x and 8x in this game) and view distance at 'High'. I have DOF and Headlight Flares OFF. I also have my game limited to 30FPS at driver level. I get decent rates between 22-30 on all routes. It drops down to as low as 11 (london brighton coming out of london with rush hour level of traffic, and WCML and WCML Over shap with decent amount of AI) in populated areas.
Shots taken on Cajon Pass.
Shot one is the way the locos are supposed to behave in the scenario editor. I get 30FPS solid with this.
Shot two is the problem. All the locos exterior lights are on, it is missing the lighting objects (I cant control the lights from the cab in the scenario because of this error) and the frame rates are destroyed!

