Bug report #5049
Data-defined labeling takes 1560% longer to render
|Affected QGIS version:||master||Regression?:||No|
|Operating System:||Easy fix?:||No|
|Pull Request or Patch supplied:||No||Resolution:||fixed|
|Crashes QGIS or corrupts data:||No||Copied to github as #:||14819|
- No labels: ~2.5 sec
- Labels with field NAME and no data-defined setting: ~8.0 sec
- Labels with field NAME and data-defined size set to POP_2000: ~41.6 sec
That's a 420% time increase over labeling with no data-defined setting and 1560% longer than no labeling at all.
Time was calculated with stopwatch, between pressing OK on the labeling dialog and when the map finally appears.
#3 Updated by Marco Hugentobler about 8 years ago
This is because in POP_2000, there are huge values. If you set the font size e.g. to 1000 (points), you get long rendering times also if the size is not data-defined.
So the longer rendering is only because the labels are larger (over 1000000 points for Houston).
#5 Updated by Jürgen Fischer about 8 years ago
Aren Cambre wrote:
Ah, so looks like resolution of #5048 might be necessary to fix this performance issue?
or by using an attribute that is usable as size - eg. by using the field calculator to produce a appropriately scaled value in an additional attribute.