It appears that the 9 cycles taken by the register value data passing through the load unit, mul unit, and add unit constitute the actual CPE (cycles per element) or critical path, rather than the xpwr path on the left.

However, these 9 cycles are only incurred during the first iteration of the loop. Each subsequent iteration requires just 5 cycles, as shown in the diagram: Paths marked with the same color in the diagram indicate parallel execution. We can observe that since the mul operation takes 5 cycles, the data's add+load operations and res's add operation can complete within this mul cycle. Specifically:

• The add+load operations for data require only 4 cycles and can finish during xpwr's mul operation.
• The res operation is shifted to the next iteration: The add operation for res in the i-th iteration is synchronized with the mul operation in the (i+1)-th iteration, effectively eliminating this overhead.

Thus, the slowest operation (and therefore the critical path) in each iteration remains the 5-cycle mul operation for xpwr.