I don't have the answer to the problem you're having, but Benchmark::timethese is definately sequencial. To prove this: 
perl -MBenchmark -le '$|++;timethese(10,{one=>sub{print"one"},two=>sub
+{print"two"}})'

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In reply to Re: Benchmark does timethese() in parallell? by Aighearach
in thread Benchmark does timethese() in parallell? by johnnywang

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