preact-virtual-list

Is it my understanding from reading the code that overscan will "align" the {startIndex, endIndex} to modulo overscan. However, I can't really see how this reduces any work in the DOM - if a continuous scroll operation results in adding 10 rows, sync mode would add them one by one (in the worst case) and overscan mode would add something like 10 rows in one operations. That sounds to me like the same "amortized" amount of work. Could you please elaborate on why this approach is more performant in terms of DOM operations? Note: I do see an obvious perf optimization in not reconciling the entire visible viewport on each scroll event - but if I understand it correctly that is only VDOM work.