We aim at the establishment of the method of controlling dialogues according to performance in computation. So that the system takes the most suitable dialogue strategy according to performance in computation, it needs to calculate evaluation functions modeled with performance in computation in the inside all time. In this paper, we propose degree of presenting process status as evaluation function and model it with computation time. Then, we simulate this model by controlling dialogue strategies. We also confirm efficiency of the model by preliminary experiment using the prototype of spoken dialogue system.