Below is a description of all the options that are available to you.
If you are looking for ways to increase the speed of Trainz on your computer, then you can decrease the Quality of Textures used in the game.
Resource Cache Size
Adjust the amount of system memory dedicated to caching. Higher values decrease disk usage during the game, but require the computer to have more system ram. If the computer has insufficient ram, performance may suffer as a result of increasing the resource cache size.
Disable Environment Map
Disable reflections and Environment Maps in order to increase Trainz framerate.
Fix Geforce3 Textures
In Version 5.13.01.2181 of the Geforce3 drivers, mixing software and hardware lighting sometimes resulted in a funky landscape. This will overcome the problem if you have that version.
Ground Polygon Offset
If you see black artifacts when running Trainz on my ATI video card, then enable this option.
Allows you to set the Vertical Sync for your Monitor. Changing this setting can help reduce the appearance of "jerkiness" on some computers. Some video drivers may have options which override this setting on a system-wide basis.
Allows you to select the refresh frequency for your monitor. Some monitors will not display certain frequencies. 72 is a good setting for most monitors.
Disable Hardware T&L
Uses System Memory instead of AGP to render Vertex Buffers. Use if you are having problems with your AGP card.
This option can enable and disable the Shadow System in Trainz. Only use if you have a powerful system.
Some video cards may require you to change this setting in order for the fonts to appear crisp, the correct setting varies depending on your video card and drivers. This slider has no effect on OpenGL.