Hi Paolo On Fri, Feb 18, 2011 at 4:47 PM, Paolo Cavallini <[email protected]> wrote: > Hi all. > I return on the old bug https://trac.osgeo.org/qgis/ticket/1978 > I have done some testing, and in fact QGIS is almost unusable with large > and complex data sets (see e.g. > https://int.faunalia.it/~paolo/slow.tar.gz ). Adding caching helps, but > this is proving to be a real stumbling block, preventing real world use > in some cases. I checked, and unfortunately proprietary sw opens the > same file much faster, and subsequent zooming and panning etc. is also > much smoother. According to the trac, also other free sw is much faster. > Can someone help me understand in which direction to work to solve this?
The main performance killer here is painting of borders. The layer is rendered several times faster if you set border style to "no pen". Also disable anti-aliasing - that also eats a lot of time. Build spatial index to speed up rendering of small parts of the map. The clear direction is to merge threading branch to trunk. It contains some optimizations for rendering, plus it does not freeze while rendering and continuously updates the map. So even when working with huge layers, it's possible to see how rendering continues and zoom/pan to desired region of interest without having to wait until rendering of the last map finished. Martin _______________________________________________ Qgis-developer mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/qgis-developer
