—The impact of shared instruction memory on performance is measured and analyzed for an FPGAbased Multiprocessor System-on-Chip (MP-SoC) with an MPEG-4 video encoding application. Our MP-SoC architecture allows arbitrary scaling of the number of synthesized processors and includes a monitoring unit for memory transfers. Based on the measurements with up to four processors on Altera Stratix 1S40, an estimate of the effect of the shared memory for larger configurations is presented. The shared instruction memory is shown to be area-efficient and sufficient in performance for configurations up to five processors, as the drop in encoded video frame rate stays below one compared to distributed instruction memory organization.