I run a modern era game (Delta Green). It tends to be feast-or-famine. If the players are doing a lot of researchy things, then I spend many an hour making up realistic handouts and writing in NPC details. Unlike in D&D, I don't have to stat monsters out as much, because in CoC monsters tend to be mooks or massively powerful without much in between. (IOW, either the players dispatch them handily or they die in the first round or two.)
I also have a brain pre-crammed full of all kind of crap about conspiracy theories, strange occult groups, weird history, etc. If I had to research this stuff from scratch it'd take longer.