Hi Gerd As you've probably seen I've added the program to the display svn as test.svg.subdiv.Main. There is an argument '--level N' to display a different zoom level. Default is 0 (most detailed). I've found that our OSM maps seem to have a lot more elements than other maps so it is difficult to compare. In general the way we create subdivisions means that many of them are quite large and they contain many elements. There are no small divisions.
If I got it right, the redraw time is influenced by a) how many sub divisions are overlapping a given bbox and b) how many objects are in these sub divisions and c) how complex the objects are (means, how much time it takes to render them)
It is also possible that the way that the divisions on different levels link together may have an effect, as it may be able to restrict the number of divisions it has to consider. ..Steve