Swap between F3 & F4

When swapping between F3 and F4 the select goes completely crazing and zooms through each one after waiting a second or two. This is also hard to show in screen-shots because of how fast it goes. I am in a world with command blocks (none that affect game-mode) but I'm unaware to why it zooms through each one in a loop. (Constantly hovers over each one very fast to the next)