[Qgis-developer] Testing/Master renders 7times slower than 2.2

[Martin Dobias]

Hi Anita

I am a bit late to join the discussion, but anyway... I cannot really
replicate the slowness you are experiencing. I can see some slowdown
which I assume is mainly related to the labeling - in 2.4 there have
been some changes that will likely slow down labeling even more - e.g.
checking of validity of polygons (due to issues with invalid polygons
from simplification) and the subsequent fixing with buffer.

For a good comparison, I would suggest to have a look where the
slowness really comes from. Apart from labeling, there could be many
more factors affecting the speed - data-defined symbology, expressions
in rule-based renderer, used symbol layers, reprojections etc.

Generally speaking, we should try to handle the performance
regressions more seriously - in the process of adding new features it
is easy to introduce something that negatively affects the rendering
speed. Radim has done some effort to build a benchmarking system for
QGIS some time ago, maybe it is time to bring it back to life and
start watching it more closely.

Btw. nice project for testing purposes. The multipolygons layer
contains a bunch of invalid geometries, it helped to find bugs in some
of the new features :-)

Regards
Martin



On Sun, Jun 1, 2014 at 7:49 PM, Anita Graser <anitagraser at gmx.at> wrote:
> Hi,
>
> I have a project with Spatialite and Shapefile layers and I found that
> it's around 7times slower to render in the current test version than
> in 2.2.
>
> The project is online, so you can try it yourself:
> https://drive.google.com/folderview?id=0Bwc-5JFVTnfIZkZOM3Y0Um9jOHc&usp=sharing
>
> I've tried different rendering options including parallel rendering
> but found no way to improve the rendering speed in Testing.
>
> I'd love to know if it's a general problem or if I have misconfigured something.
>
> Best wishes,
> Anita
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