the crash is that the game just freezes and since waiting half an hour didn't help. I chose to shut it down using Windows Task Manager. And I don't have any mods that change anything associated with my defenses. I could list them if you want to know them?
4.9K? xD that's laser turrets. with about 2k normal turrets..
But without the mod it works fine. Not even a stutter in all of my games. The only reason I can think of why it becomes to heavy is that it has to do the calculation for every turret separately. isn't it easier if that calculation is done once for all of them? or am I suggesting things that aren't possible?
I think your issue might be the sheer number of turrets. Every time you update the range research they all need to be upgraded. This cannot be avoided, and must take some minimum amount of time, per turret.
I have tested it on large bases, but not memetic "megabase" "1 rocket per minute" setups, as my worlds never last that long and it is not feasible to make one for the sake of testing.
