Switching speed of longitudinal thin film recording media was studied using micromagnetic modeling. The dependence of the switching speed on the damping constant a was investigated. It is shown that when a is small (=0.01), even with instantaneously rising head field, the medium switching time can be as large as 2 ns, which is slow enough to have a significant impact to the high frequency recording. Nonzero head field risetime can significantly decrease the medium switching speed. The impact of finite medium switching speed and nonzero head field risetime on recording performance is estimated.