During the guy fight, kakashi said his eyesight was getting bad hence why gaara had to use sand to get him up close to kamui snipe madara's shield. Kishi just became kinda inconsistent near the end. In p1, just using the normal sharingan a lot put him to bed. Now dude spammed god knows how many kamui, although naruto did refuel him some times. But I still felt like kakashi wasn't really showing as much suffering compared to how say Itachi started getting tired immediately after tsukuyomi, and how sasuke's amaterasu kept making his eye bleed.