In general it is not possible to implement the “endless data” PDF output in HTML-to-PDF conversion scenarios.
PD4ML does all the layout of all the pages in memory, before it writes anything out. The reason is following: let’s say the source HTML layout is built as a single huge table. Any cell, let’s say, on page #350 whose width is a bit wider than previous cells of the same column requires re-layouting of previous 349 pages – as it impacts the entire table layout. If the 349 pages are already written to an output stream – the re-layouting is not possible anymore.