The switching efficiency of nonlinear optical loop mirrors in which the wavelengths of the control pulse and signal solution straddles the dispersion zero was investigated numerically. In our analysis, the effects of control pulse parameters such as pulsewidth, central wavelength and jitter on the switching efficiency of soliton NOLM were considered. The required peak power of the control pulse to achieve maximum switching efficiency was found to decrease in as the width of the control pulse was increased. This is mainly due to the combined effect of self phase modulation and positive group velocity dispersion of the control pulse. In this paper we also show that the maximum switching efficiency of NOLMs with loop lengths of one and two soliton periods long, can be achieved with control pulse of reduced peak power if its pulsewidth is three times of that of the signal. Jitter, and wavelength detuning of the control pulse reduced the switching efficiency of the NOLM. However, more than 90% switching efficiency could still be obtained even when the control pulse central wavelength is detuned by about 4 nm or when the control pulse jitter is about 26%.