The evolution of hot spots at defects in a 3D fee lattice under rapid 1D compression along different crystallographic directions has been studied by mean of molecular dynamics. Hot spots were generated in monatomic and molecular crystals when the strain energy released through defect-mediated structural relaxation was locally converted to heat. Thus, hot spot temperatures are shown to be controlled by the potential energy source of the strained lattice and by the allowed extent of structural relaxation.