I'm looking at QGIS 2.18.9 and using a polygon to select points from a large point layer (file based tab file).

I wondered why the process is so slow if you use plugins or analysis options? I ask because simply drawing the same polygon with the select tool works in seconds.

Tools tested include the intersection tool and Select Within plugin.

If the select tool is so much faster, is there not scope to improve the performance of the analysis in QGIS?

  • Have you tried creating a spatial index for your point layer? (in layer property>General -> create spatial index ?
    – Blue
    Jul 19 '17 at 15:21
  • Yes, the layer already has a spatial index but thanks for your comment. Jul 24 '17 at 14:35
  • Related: gis.stackexchange.com/questions/182716/… Dec 20 '17 at 7:29

Select is a core tool in C++ and the others are Python tools. You'll be happy to hear that, for QGIS 3, there is work on porting essential Python Processing tools to C++ under way.

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