Describes a powerful post-synthesis approach called reclocking, for performance improvement by minimizing the total execution time. By back annotating the wire delays of designs created by a high level synthesis system, and then finding an optimal clockwidth, we resynthesize the controller to improve performance without altering the datapath. Reclocking is versatile and can be applied not only for wire delay consideration, but also for bit-width migration, library migration and for feature size migration supporting the philosophy of design reuse. Experimental results show that with reclocking, the performance of the input designs can be improved by as much as 34%.