Optimizing a Scene

Actually I create a Intro-Animation and i would say it is not finished like this. But I got problems rendering it now.
I think that the szene is too complex and would be glad if someone would look over it and tell me what I could do better.
In my opinion the main issue are the particle systems. The orginal szene is with linked objects.
For the Volunteer request i append everything. Maybe that could be an issue too.
Dropboxlink: Everything is Hidden!


I just had a quick look at it, and seems that the particles systems would slow the render, but they are probably necessary to the animation. Are you having issues with render time? If so, what are your computer specs?

My PC is very old now but the most render I took so far didn’t need that long to render.
NVIDIA GeForce GT 440
Intel i7-2600 CPU @ 3.40GHz
6 GB Ram