Issues with instant scrollBahaviour and i show add throtlling to the onBlockIntersection function

[Mood-al]

There are and issue when i set the scrollBahaviour to instant and the problem is on first load or render the onBlockintersection function is passing incorrect index because of the scroll that happens on browser preserve scroll position mechanisim!.

I should add some kind of throtling or awaiting on onBlockIntersection to delay it from firing until the page scroll ends and this will fix many issues and it will be way performant than the current using.