A new computationally efficient ion implantation damage model has been developed and implemented in UT-MARLOWE Version 4.0. Based on the modified Kinchin-Pease formula, this model accounts for damage generation, damage accumulation, defect encounters and amorphization. With two parameters, one species-independent and the other species-dependent, good agreement with experimental impurity profiles has been obtained for sufficiently low energy implants. In addition, the amorphous layer thicknesses obtained in this model are also in reasonable agreement with experimental measurements. For higher energy implants, another parameter is introduced into the model to remedy a deficiency of the conventional Kinchin-Pease model. With this modification, good agreement with experimentally measured impurity profiles has been obtained for implant energies up to 65 keV for BF2, 80 keV for boron, 180 keV for arsenic and phosphorus over a wide range of doses (1 X 1013 cm-2 to 8 X 1015 cm-2) and tilt angles and rotation angles. In combination with other CPU time reduction techniques, a speed improvement of up to an order of magnitude has been observed.