I was messing and tried comparing the performance of different ways to compute the factorial of a number. Here's the benchmark results:

recursive:	244 ms, 283 μs, and 2 hnsecs
loop:		241 ms, 412 μs, and 3 hnsecs
parallel:	1 sec, 784 ms, 829 μs, and 5 hnsecs


https://run.dlang.io/is/uyVlqu

I was quite surprised by the fact that parallel ran so much slower than recursive and loop implementations. Does anyone know why?

On Friday, 24 August 2018 at 13:04:47 UTC, Uknown wrote:
> I was quite surprised by the fact that parallel ran so much slower than recursive and loop implementations. Does anyone know why?

n = 100 is too small to see parallelism gains.

Try n = 10000

https://run.dlang.io/is/XDZTSd

On Friday, 24 August 2018 at 20:43:46 UTC, Peter Alexander wrote:
> On Friday, 24 August 2018 at 13:04:47 UTC, Uknown wrote:
>> I was quite surprised by the fact that parallel ran so much slower than recursive and loop implementations. Does anyone know why?
>
> n = 100 is too small to see parallelism gains.
>
> Try n = 10000
>
> https://run.dlang.io/is/XDZTSd

I was using n = 10000 originally, I reduced it because that wasn't running on run.dlang. Tried this again on my machine and you were right.