The CPU is already working at 100% calculating the number.

Yes, one core is working at 100% to calculate the product. By splitting the list in half, two cores are working at 100% - the OP cites having a dual core. It just so happens that in this case:

loop_overhead + n*multiplication < thread_overhead + loop_overhead + (n/2)*multiplication

as I would expect for this kind of simple operation. But throw in transcendental functions and maybe the balance shifts.

In reply to Re^3: how to multiply an array of number as fast as posible by kennethk
in thread how to multiply an array of number as fast as posible by baxy77bax

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