Board Thread:Theories and Speculation/@comment-36512555-20200101053037/@comment-38812954-20200101180329

Vs Sasuke, after asking Sasuke, 'How much can he see with his Sharingan.' And Sasuke told him he saw him dead. Itachi zipped to Sasuke's side fast as hell (most likely using the body flicker technique) and told him, 'well make it happen.'

In the same novel that Rallo is referring to ^^, in the chunin exams. Up against a three man team from another village (that happened to have the opposite scroll he needed to clear the exam). To avoid any prolonged fighting (They had a little scuffle before this) he sped up behind each of them, knocked them out and went on ahead to finish the exam (Chopped them in their necks; He scared them in the scuffle, and they willingly gave him the scroll. If I remember correctly)

Vs Kakashi and co in part one. Kurenai (After she narrowly escaped from Itachi's attack; Releasing his reverse genjutsu) lept over into the water, and as soon as she came to to gauge Itachi's whereabouts. He was instantly right behind her.

I think he more or less uses the body flicker technique, or simply his chakra to amplify his speed (like Sasuke does).