Why override scrolling for this fake "subpages within a tall page" concept? It feels horrible, at least on a MacBook Pro trackpad. Maybe it's fine on a mouse.
I use arrow keys/page up/page down. It works well, but that's hardly normal.
It makes my CPU fan spin up with 100% utilisation of one core and does not let me scroll. Definitely not looking forward to visiting it again.
For me, it worked smoothly - may be a browser issue.