Piling on here. I've experienced the same thing as everyone here. Super happy to find this forum.

I'll note three things, however:

1) As a child, it almost always happened very in the morning (Walking the dog, taking the shower, etc.)

2) There is a feeling that preludes the fast feeling, and I can feel it coming on before I actually "speed up." I can't really describe the feeling, but here's a shot: it is like a bulge in the back of my throat and I can see a ball (or something) in space. The ball is not whole, it is somewhat cracked open. When I feel this I push it back down before I start going fast.

3) There is a book called the Politics of Experience that mentions something eerily similar in the 2nd to last chapter of the book. Its a reference to Jesse Watkins who underwent an inner experience that sounds like the DMT experience AllTheWay mentions a few pages back. Perhaps linked to meditation or breaking off from our ego for a moment.