Interesting, I wonder if this is the thing that happens to while playing this videogames. At some point after hours (30+) struggling against the same boss,you realize you see everything in slow motion,at that point you know it's the end, you mastered it. I literally say "ok it's done, time to defeat it".
Is this Chi
I always thought of it as muscle memory, the movement becomes so ingrained in your body that you can focus on things at a higher level. Keep going up the levels and at some point everything looks like trivial details
Based on my own experience, it's nothing like chi or something supernatural. The repetition has lowered the uncertainty of the thing you're trying to do, to the point it's easy to do if you focus.
That's it, experience and focus. Even if you mastered something, someone can keep distracting you and you will find it returns to difficult without focus. Even if you focus a lot, hard things have to be repeated to master them.