Board Thread:Naruto Discussions/@comment-26107879-20181004003653/@comment-33048698-20181008184347

The chidori unintentionally increases one's speed. It was created as an alternative to the rasengan because kakashi couldn't add his nature to it.

Kakashi thought he had created an assassination jutsu that could be used to pierce anything at any speed. But The manga shows that when lightning chakra is flowed into and around the body, their raw speed and reaction time is increased. The chidori increases the users cutting power, speed and defense(well the both of them never seem to complain of finger pain from hitting rocks.), but it does not increase the users reaction time to any noticeably advantegous effect.

The only way to counteract this defect of the chidori is to use chakra flow and coat ones body in raiton armour(which kakashi lacks the chakra for) or to implant a sharingan(like he did with obito)