Suppose you have measured the percentage of encryption to be 50%. The hardware design group estimates it can speed up the encryption hardware even more with significant additional investment. You wonder whether adding a second unit in order to support parallel encryption operations would be more useful. Imagine that in the original program, 90% of the encryption operations could be performed in parallel. What is the speedup of providing two or four encryption units, assuming that the parallelization allowed is limited to the number of encryption units?