So I was looking into whey products and found out that Whey Isolate is fast digesting and Whey Concentrate is slow digesting. It was mentioned in reference with other supplements whether or not they contained lactose also. My question basically is, what are the benefits or uses of a slow digesting supplement as opposed to a fast digesting one? I assume the note about containing lactose is with respect to people who are lactose intolerant, but if that isn't all of it, then the same question.

TL:DR comparison between fast digesting and slow digesting whey supplements, does lactose matter in your whey product beyond a lactose intolerance