total solution time in dynamic explicit analysis

Hello,

 I'd like to know how the computation time depends on the element number in a model (dynamic explicit analysis in Nastran). When I work with a simple model which has a rather coarse mesh the function is linear, so 10 steps with the increment 0.001 is equivalent to 100 steps with the increment 0.0001. But I don't know how this dependency will evaluate if I build a much more complex model. Maybe it will be exponential?

Thank you