A FEW TIPS TO MAXIMIZING YOUR SYSTEM'S PERFORMANCE FOR TRAIN SIMULATOR
1. PROFILE YOUR VIDEO CARD
The first step is to let Train Simulator Profile your video card. This process will automatically adjust Train Simulator to run best with your video card. You can make your own adjustments later, but this is an important step.
Go to your Programs Start button and locate the 'Train Simulator Troubleshooter' line and then click on 'Change Video Driver'. That's all.


2. ALLOCATE SYSTEM MEMORY FOR TRAIN SIMULATOR
You can increase the memory dedicated to MSTS using the added parameters to the program's target line.. For more info on that you can check out the author's full tutorial: http://msts.steam4me.net/tutorials/xtra_mem.html
By right clicking the MSTS icon on your desktop, you can alter the target by adding one of the following(in blue):
...train.exe" -mem:512 for playing MSTS full-screen or
...train.exe" -vm:w -mem:512 for playing MSTS in a window

3. GET BIN
Bin is a 3rd party update to Train Simulator that we could simply not live without! Download the latest version of Bin from the website and install it. Make sure you already have the first(and only) Microsoft update released in 2002 TS Update 2002 before installing Bin:
Get Bin Here
look for Download page(looks like this)
Another simple tweak you may want to make on your Windows 7 system is running Train Simulator in 'Compatibility Mode'. Just right click the Train Simulator icon on your desktop and select 'Properties'. Go to 'Compatibility' and check the box for 'Run this program in comptibility mode for: Windows XP(Service Pack 3).