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  • $\begingroup$ Looks like your method is five times faster than the next best! Can you give some insight into why this is? Thanks! $\endgroup$ Commented Mar 27, 2019 at 15:34
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    $\begingroup$ Also, and I guess this depends on the probability of any entry being negative, it may make sense for the algorithm to stop as soon as it finds a negative (or non-positive) element in the list. $\endgroup$ Commented Mar 27, 2019 at 15:37
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    $\begingroup$ @mjw, And[] does short-circuit evaluation. $\endgroup$ Commented Mar 27, 2019 at 15:41
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    $\begingroup$ @Bob, Thank you for your edit. Why, though, does it take longer for your method to work when there is a negative entry? I would have thought that in each case, it would take the same amount of time to go through the whole list. $\endgroup$ Commented Mar 27, 2019 at 16:03
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    $\begingroup$ @Roman, I do not believe that any lazy evaluation is being done. My comment was more to point out that an evaluation like And[True, True, False, True, True, ... True] will finish at once (and similar remarks apply for Or[]). Perhaps one can judiciously use Catch[]/Throw[]if an early-return test for long lists is desired. $\endgroup$ Commented Mar 27, 2019 at 16:06