This paper analyzes the simulation operation flow of Bullet physics engine. Based on this analysis, four kinds of multi-rigid-body game characters are designed. This paper also profiles the performance metrics such as the CPU utilization, the memory usage, and the computation time by multi-rigid-body character simulations. For the CPU utilization, the Tongs Vehicle is the best and provides 45.1% less than the other character simulations. The computation times of the Four-leg robot and the Dragon are longer than those of the others. The memory usage of the Dragon simulation is the largest, which is average 1.32 times more than the others. Because all parts of Dragon are composed of triangular mesh models in 3DMax. The performance profiling with the criteria such as reducing the computation time and the computing resources, the complexities of the collision shapes, and the number of rigid bodies takes an important role in the design of the multi-rigid-body game characters.