Here's my experience in what works to help mitigate the crashing damage.
1. verify your files on steam. Go to library>TWW3 on the left hand side>right click, go to properties>Local files tab>verify integrity of game files. let it run and repair anything that needs it. Seems to help some, still have some crashes after but not as frequent
2. Ctrl+S is your best friend. Constant quicksaves so you dont lose work is a necessary evil at this stage
3. Update your video drivers if you dont have a program that does it automatically. I will leave you to google this one.
So far that has made the game playable for me, it still crashes but since I dont lose a ton of work and It no longer crashes after <2 minutes consistently, its playable. Of course its only the overworld map that crashes for me so if yours crashes in battle it may be a different problem.
Hope this helps, leave your fixes or experience below.
Thanks for reading.