[Raapys]

No offense, but if you're talking about the DD-Duc 2 destroyers, then I'm afraid you've gone the wrong way when designing. Your problem is that you've filled it with guns; as it happens, armor > guns. Your FF-Escort-2 has far more armor and therefor easily wins against your 1-armor destroyers.

To see what I mean, copy your FF-Escort-2, remove one of the guns and fill in the freed tonnage with more armor. You'll see the new ship you just made beat your old frigates.

Also note that the actual size difference between the frigate and that destroyer is only 25 tonnage. I.e., tiny.

How do you manage to play with that camera angle O_O

I'd suggest you get a hold of the Balance Mod if you haven't tried it already. The number of issues it fixes is immense. It changes research slightly( fewer and more expensive tech levels instead of cheap and many tech levels ), but it is basically the same game, only better.

Not sure about the crashing problems. Think there was a few others who had it as well. Do you happen to have a dualcore CPU or some such?