Each update improves the optimization, 4.0.0 is really better than all previous versions but a 10 year old PC can be difficult to use, I like to use new technologies to make the game look good and old PCs have a hard time making it work properly.
That's very understandable. And the games progress/quality should not be sacrificed for just a few that can't or won't upgrade their hardware. I've had very few games that I couldn't run up till now. And I know it's long over due to get a new comp, its just going to get worse for me the longer I put it off. Good luck on the game, and when I get a new one I'll be back