  We discuss the computational performance of the adaptive resolution technique
in molecular simulation when it is compared with equivalent full coarse-grained
and full atomistic simulations. We show that an estimate of its efficiency,
within $10-15\%$ accuracy, is given by the Amdahl's Law adapted to the specific
quantities involved in the problem. The derivation of the predictive formula is
general enough that it may be applied to the general case of molecular dynamics
approaches where a reduction of degrees of freedom in a multiscale fashion
occurs.
