I don't think this really has anything to do with C#, but it can be awnsered regardless. The current biggest throttle point by far for Aurora is that everything is saved and loaded directly to the database, every time, without really living in memory. Your CPU has very little to do with the throttle, its all about disk access. Using an SSD or a RAMdisk can help, but its still a large number of operations that have to be performed just to update a fleets position, or a planets position. CPU centric operations like AI decisions, or damage/detection/combat calculations are a far smaller part of the turns right now.
C# heavily cuts into this by keeping content in memory when possible, cutting out all those save/load operations that are constantly being performed. Steve's already posted some preliminary numbers showing significant increases.