Higher resolution, higher FPS? (slightly)

[Vegetable]

So, yeah. Today I got my sorta fancy LG 24MP58VQ. Just your run of the mill 1080p 60hz IPS monitor. Colors are FANTASTIC, and it's nice the finally be able to say I even own a 1080p monitor. I upgraded from an Acer X223W, which was 1680x1050. Not a HUGE resolution jump by any means, and the switch to 16:9 aspect ratio was pleasant to say the least. One thing I did notice though, in a of couple games (BF4, GTA V, and DayZ) I got an FPS boost. oddly enough. You heard that right. All my graphics settings are exactly the same, and somehow in GTA V, I no longer at ANY point in time, drop below 60fps. On my old monitor, in specific areas (such as anywhere north of mount chiliad) it would drop to the mid 50fps range. Not a problem at all for me, but oddly enough that no longer occurs. Again in BF4, I have it on the ultra preset with the resolution scale set to 150%, and it runs perfect 60fps. On my 1050p monitor it would, again, drop into the mid 50fps range. DayZ is an unoptimized PoS, but my FPS refuses to drop whatsoever now. So, I've come to the conclusion that below 1080p, games (or at least these games) become more CPU intensive than GPU intensive, effectively the opposite of running a 4k monitor, which we all know, is FAR more GPU intensive than CPU intensive. Thoughts and input on this conclusion?