Assume no superko rules so the game would end with no result. And both players are willing to play the shortest possible cycle as long as they don't give their opponent a chance to win.
Molasses ko: http://denisfeldmann.fr/bestiary3.htm#mol
"The semeai in figure 11 is probably the worst known case of repetition. Known as "molasses ko", ..."
Denis Feldmann's Go Bestiary is a compendium of various things (interresting semeai, life and death, edge cases, incredible problems, rules edge cases, weird sekis, etc).