Two ideas:

  1. The sort() is probably the most expensive thing you are doing. With the code snippet you've provided, there doesn't seem to be any need for it. If you really need the sort, sort the matching results rather than the input list of keys.
  2. Are you really doing anything with the (.*) portions of the regexen ? Reducing the regex to /^$combine/ would speed it up ( and the other one to /$combine$/ ).

    In reply to Re: Fast sublist generation by kschwab
    in thread Fast sublist generation by PetaMem

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