A two-stage detector is proposed to accommodate high computational load requirements of modern radar systems. The first stage of the proposed system is a low-complexity detector that operates at an unusually high false alarm probability value around 1/10. This stage is to prescreen and eliminate some of the test cells with relatively few operations. The second stage operates only on the cells passing the prescreening stage and implements a high-complexity detector at a desired system false alarm rate. Due to the detector cascade, the second stage has a large amount of computational load reduction, on the order of 10 folds, in comparison with the single-stage systems. The mathematical analysis of the described two-stage detector is presented, and the relations for the false alarm and detection probability are derived. The numerical results show that it is possible to achieve a significant computational load reduction at a negligible performance loss with the proper selection of detector parameters.