4k is 4 times the size of 1080p (it's twice the width and height, so 4x the number of pixels), and 2.25x 1440p (1.5x per side), so assuming that there is absolutely no time loss between frames, you are looking at 1/4 fps on a 4k than 1080p, and 4/9th fps than 1440p.
It would be slightly harder to power a game at 1440p @ 144fps than it is to power it at 4k@60fps if counting only pixels and not including any hardware bottlenecks that may occur, though not by much. However 1440p @ 72fps is much more playable than 4k @ 30fps for example.
Also, it would be much easier for a GPU to render 1080p @ 144hz than @ 4k, as 1080p @ 144fps is equal to 4k @ 36 fps, again ignoring any hardware bottlenecks in the system