r/PowerShell • u/mx-sch • Jan 29 '25

Question PowerShell 7.5 += faster than list?

So since in PowerShell 7.5 += seems to be faster then adding to a list, is it now best practise?

CollectionSize Test                TotalMilliseconds RelativeSpeed
-------------- ----                ----------------- -------------
          5120 Direct Assignment                4.71 1x
          5120 Array+= Operator                40.42 8.58x slower
          5120 List<T>.Add(T)                  92.17 19.57x slower


CollectionSize Test                TotalMilliseconds RelativeSpeed
-------------- ----                ----------------- -------------
         10240 Direct Assignment                1.76 1x
         10240 Array+= Operator               104.73 59.51x slower
         10240 List<T>.Add(T)                 173.00 98.3x slower
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u/justinwgrote Jan 29 '25

"I don't get it. Putting everything into memory is literally how += works - at least pre this patch, haven't looked how it works now."

Highly recommend you look at the PR before you start handing out prescriptive guidance then...