would say no, just kill as fast as u can with as much Magic Found as u can

On some maps or in some dungeons you can find a NPC who has the name "Zeitgeist". She sells one or two uniques, legendarys sometimes and always the highest gem tier which you found so far.
Keep your eyes out for her, because she can spawn everywhere and she doesnt have a minimap-icon. (I hope they patch one in for her ;) )

She does have a mini-map icon, its a bag, just like the shop icons.

She can spawn both with or without a bag icon.