Improve rendering performance
As in many others apps, you should take care to trick your scene to get faster renderings. But you also need to just improve your rendering power.
3D Video card
While your are in 3D modeling, 3D video cards only do the drawing on the scene, not the rendering. You may have the best 3D card, you won't get rendering any faster. 3D video cards are only useful if when you turn around the scene in 3D view, you feel a bit stuck.
What you need most in rendering is CPU power. multi-cores worth the price as you really get faster. 2 cores = 2 times faster!
Useful on large scenes or well detailled. Increase if you use many textures, lot of polygons or animation baking. You can see the amount of memory used on top of the rendering screen, near the rendering time.
Official builds of Blender are designed to work on all CPUs. Therefore, the software is not properly optimised to yours. Get an optimised build can increase rendering time by 2 !
It's well know that Linux has a better memory management than Windows. It's also lighter and do better multi-tasking. Therefore, switch to Linux could get your rendering ever faster.
This benchmark should give you an overview of CPUs and operating systems performance with Blender.