alt Hacker News> FPS based on last frame is good to see load spikes, particular periodic ones, if you graph them.
This.
The other two are not good for anything gaming as any framerate inconsistency breaks the experience. A stable frame rate is much more important than a high one.
The point is that if you’re not doing perf analysis and logging/graphing but just want to display FPS to the player, last-frame FPS is pretty useless because the number changes too fast.