Season 5 – “wind style shuriken” to “a place to return to” episode 89- 112 watch episode 88 and 113.This is when all the yukimaru stuff happens and the akatsuki catch the 3 tail beast. Not really filler because it is in the manga but pretty boring just a little bit of sasuke but not much. The main sasuke stuff start at the serpents pupil which is episode 89 season 6.
Season 4- deprived of eternal sleep to the quietly approaching threat episode 57- 71 watch episodes 56 and 72. This is when all the sora stuff happens. Definitely filler episodes. These episodes are not in the manga and you can’t even notice that you have skipped about 16 episodes. But it has a lot of fighting which you might want to watch but they don’t talk about it one bit in the episodes after it.
sam