Results are scattered along the thread. But here is a resumen of it:
The static objects, like systems, planets, bases, and that kind of stuff does not affect lag.
What affect lag are the moving objects, and the IA. The IA is calculated on the server, so everybody sees the NPC doing the same. The moving objects are calculated on the server too. That is what I can see through the game behavior, and is the most logical course of action to take. If IA were calculated client side, then two players in the same place would see NPC doing different things. Take as example the starcraft game recordings. Every time you play a recorded game, it ends different. Because it only saves seed info, and leaves the IA to do the rest.
So, the more NPCs and players out there, the more processing power and bandwidth we need.
So:
--We might need to save for a more powerful server. Something along the lines of an A64 3500, or a Pentium D 805 overclocked to 3.6 Ghz. (the PD 805 is slow on stock speed, but quite cheap. And can OC a lot and became very fast), would be cheap and quite fast for the server. I think that processor is the cheapest Dual core money can buy, and overclocks a lot with stock cooling, so we can get a good bang for the buck.
--We can always put less NPC out there, but i don't think that would help as we still have many players on server and it's not a solution, is only a way to postpone the problem.
(If you find any mistake in my English, please let me know via a PM)
(Really, I speak terrible English, so please, tell me if I make mistakes. I'd like to improve it a bit )