Board Thread:Theories and Speculation/@comment-36512555-20200101053037/@comment-9782468-20200107141546

Sasuke described his technique as his final technique and noted that Itachi couldn't dodge. Then raised his whole arm above his head, and swung it to well past his waist, which is one visual indicator (Itachi still had one working Sharingan. Though the eyesight was blurry, it could still see and even from that distance, the movement itself would be noticeable, even if he couldn't make out the exact form).

And then he saw the sky get brighter, after all that. So yeah, Itachi had some set up.

Considering Kakashi was a kid (or a teen or whichever), I'd say it's still pretty impressive. Sure his eyesight was fine, but remember he wasn't even a master of the Sharingan when he was a full grown adult. He gained much expertise, but he was never on the level of Itachi, and he certainly wasn't as good when he was that young.

Yes it's all impressive that Itachi reacted to Lightning (with all the set up included), but considering Kakashi did it as well, it's not super impressive. Especially given that even though Itachi was sick, he was still way more formidable than Kakashi, and that's been well established. So Itachi managed to do something sick and blind that Kakashi could do at full health. All I'm saying is it adds up and all in all is not the most impressive thing compared to some other feats in the series.

It also comes to my attention that this tangent is pretty off-topic, since the OP wanted travel speed feats lol