We examine an opportunity for increasing cyclic process efficiency at the expense of taking into account speeds and times of running processes. We consider dynamic equilibrium systems, in which the equations of state include both parameters of the system and environment. At low flow speeds, conventional quasi-static methods apply. At high speeds, new regenerative cycles become possible. This requires the introduction of an extended interpretation of the second law of thermodynamics. This involves specifying the performance of a cycle by the relative difference of temperatures of the working fluid (but not of thermal sources) at the upper and lower temperature levels of the cycle.