Configurable architectures have emerged as one of the most powerful programmable signal processing platforms commercially available, obtaining their performance through the use of spatial parallelism. By changing the functionality of these devices during run-time, flexible mapping of signal processing applications can be made. The run-time flexibility puts requirements on the reconfiguration time that depend both on the application and on the mapping strategy. In this paper we analyze one such application, Space Time Adaptive Processing for radar signal processing, and show three different mappings and their requirements. The allowed time for run-time reconfiguration in these three cases varies from 1 ms down to 1 µs. Each has its own advantages, such as data reuse and optimization of computational kernels. Architectures with reconfiguration times in the order of 10 µs provide the flexibility needed for mapping the example in an efficient way, allowing for on-chip data reuse between the different processing stages.