I have been building consists for quick drive scenarios without major problems.
It is true it takes forever the first loading, more than 5 minutes I think.
I have used those consists even to test mods so I have been building and deleting consists with some frequency.
But I believe I have had no more than a couple crashes in the last 3 months.
What is still a mystery for me is to learn how to find these custom QD consists, when using the scenario world builder.
If anyone can help with this.....
