I have to find all distribution list that are in 3 different public folders

Right now, I'm setting my folders and I doing a loop like this :

VB Code:
  1. For each myObject in myFolder

  2.   If myObject.Class = olDistributionList then

  3.     'Add it to a ComboBox

  4.   End if

  5. Next

The time to search in the 3 public folders and listing all DL takes about 3 to 5 minutes.

What is the fastest way to do this ?