In global navigation satellite system (GNSS) receivers, matched filters should be applied in time delay estimation to maximize signal-to-noise ratio of tracking loops. Integrate and dump filters are often used as a simplification to reduce hardware cost; however, there is no quantitative conclusion about its performance degradation yet. To deal with this issue, analytical expression of performance degradation is derived, and Monte Carlo simulations are given to support the analysis. Theoretical and simulated results show that the performance degradation is about 0.44dB if sampling frequency is twice of signal bandwidth, and it can be neglected if sampling frequency is increased to four times of signal bandwidth.