Detailed Timing:

Clock Period (T) = max( clock period for each state )

T > 32 ns, F < 31 MHz

This assumes that the controller delay does not limit the performance.

Conclusion:

COMPUTE_SUM state does most of the work. Therefore most of the components are inactive in GET_NEXT state.

GET_NEXT does:

Memory access + ...

COMPUTE_SUM does:

8-bit add, Memory access, 15-bit add + ...

Move one of the adds to GET_NEXT.