As each dead Visionary gives more than 10,000 Residuum (looks like it's between 10,000 and 15,000), you can get this achievement easily by killing at least 2 Visionaries on a single map. Don't bother trying to kill every enemy on the map.
I personally got it by killing Aleksis and Egor in Updaam (night) at Aleksis' party after completing the quest 'Lost in Transmission' before.