Game engine just got a huge speed bump!
As of Blender 2.71, the animation system in the Game Engine is fully multi-threaded. By dispatching each object’s skeletal or shape key animation to a different thread, the new version is able to put multicore CPUs to much better use than before.
From my testing, Blender 2.71 is more than twice as fast as Blender 2.70 running a test scene with 242 objects with a total of 1210 bones (5 bones each). This means for a complex scene, the Game Engine can now handle a lot more animated characters than before!
As seen from the graph, the CPU usage is also significantly higher across different threads, proof of multi-threading at work.
This improvement is available and enabled by default in Blender 2.71 or later.
Test system is a i7 Macbook Pro with 4 physical cores (8 Threads).