Rating: The issue is technically (code) related.
Issue: Mouse lag when NPCs are spawning, PC freezes
Reason: The freezing occurs when NPC Ships are not cached by your Game.
Solution: One solution is getting more ram for your pc or simply “make it faster” by a faster cpu. Often it helps to defrag your PC on a regular base. Still their is no real solution for this Problam than putting as much as possible power to the Game. The Freelancer Community is working on a solution.