This paper continues the process of reconciling results obtained when investigating heat transfer in the supercritical liquid–vapor region inherent in stationary and fast processes. A relatively simple model of non-stationary heat transfer at the microscopic level in a non-idealized system is constructed. The model provides a possible explanation for the increase in the thermal resistance of a supercritical fluid (drop in heat conduction) at a not too great distance from the critical isobar on a scale of small characteristic times and sizes. The model is based on an explicit account of a significant decrease in thermal diffusivity when approaching the critical temperature of the substance. The simulation results are compared with experimental data on the rapid (lasting in units-tens of milliseconds) transfer of a compressed liquid to the supercritical temperature region along a supercritical isobar.