You can use various colors of green texture to simulate grass. This is what I do in my very extensive layout. I would love to have lots of tall grass, bushes, and weeds, but there's that compromise that Mike mentions. I would rather roll along rather than crawl and studder along.
You might also try removing hidden trees. I made this mistake very recently when I did some route building. I built whole forests, which looked very nice in Surveyor, but when I got into Driver, my PC shuddered and stuttered along when I got to these sections. I then went in and deforested the areas away from the tracks and avoided any areas that could be seen from the cab view. This was a matter of clearing the backside of the hills and mountains that would never be seen even though it would have been nice to have a somewhat realistic forest. Once I did this the performance was like night and day without the extra trees. Now the train can move along at 60mph without stuttering and shuddering along as the computer fights to display the objects, handle the AI processing requests, and everything else that goes on in Trainz at the same time.
There are also other things to try that'll help your framerates from a system standpoint.
1) Defrag your hard drive.
Trainz loads the objects off of your hard disk into memory for display in the game. As you move along in driver, these objects get read at a rather fast pace. There's a possibility that if your drive is highly fragmented it will take longer loading in the data. This will delay the displaying of the objects and cause the program to studder along. I defrag my PC at least once a week and more if I'll be using Trainz. With a defragmented drive, Trainz not only loads faster, the overall performance is much smoother.
2) Ensure nothing else is running at the same time.
When running Trainz, make sure you shut down any Internet browsers, chat programs, video, and even music players, etc. One of the biggest culprits, believe it or not in system performance, is the Windows Search Indexer. This is a built-in service that MS Office will turn on so you can find things "faster" when you search your hard drive. Once it's enabled, it will drag down the performance horribly as it builds a database of files on your system for future searching. I've disabled the service so it never comes on. The performance difference is like night and day.
3) Ensure you have plenty of disk space and plenty of SWAP file size.
Even on a modern system with plenty of memory, the OS will use virtual memory and programs will use temporary space. If there's not a lot of disk space, there is a bit of a fight as the OS and program try to run at the same time. As your program runs, it will build temporary files that it reads and writes to and from. If there's not a lot of disk space, then there's a lot of "disk thrashing" happening on. This mechanical operation will slow down the performance of the PC and cause programs such as Trainz to slow down even more.
I hope this helps, as we think of different things, we'll post them. I think your biggest culprit is too much of a good thing as many of us have found out the hard way. It's easy to get carried away in Surveyor and place way too many objects for your computer to handle in Driver.
John
