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I'm trying to do some clip process with a quile large layers but the process is too slow. When I see the task administrator, just around 28% of the CPU is being used. I've tried with 32-bit and 64-bit versions of QGIS 2.8 and 2.12. Same results: A clip of this layer takes hours, while ArcGIS 10.2 just needed 2 minutes. Does someone know what could be happening ??

Vince
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César Arquero Cabral
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    So big difference must have a reason and using raw power is not the right solution. Would you be happy with 100% cpu usage and process still running for an hour or two? My bet is that QGIS does not utilize spatial index for selecting the candidate features for clipping. Describe your case in QGIS mailing list and perhaps developers will make a real fix in the future. – user30184 Feb 09 '16 at 14:09
  • I know that you can enable multiple-core processing for visualization and rendering by assisting the rendering settings in QGIS. You can also enable 64 bit GRASS algorithms through the toolbox manager. Is it possible that the algorithms that QGIS relies upon for what you're doing are primarily built for 32 bit processing? – Trevor J. Smith Feb 09 '16 at 16:04
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    That's odd, especially considering reports such as http://www.donmeltz.com/arcgisqgis-faceoff/. Which data sources are you using? Can you share test data? – underdark Feb 09 '16 at 17:46
  • This folder contains the layers that I want to use. As I told you, the process in QGIS was awful (several hours). You can try and see how can I improve the performance. https://www.dropbox.com/sh/c7imdudvfl70um9/AACfC4a_ud0VfEWDvvNCMLMya?dl=0 – César Arquero Cabral Feb 09 '16 at 23:19
  • Disk load goes to 100% using QGIS 2.12.3 geoprocessing clip with your files what disk are you using? (solid state drive would be faster) would suggest using postgis and clip files from that. – Mapperz Feb 10 '16 at 05:07
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    I've got the same problem using disolve, it takes too long. As you can see in the image, CPU is at 28%, disc usage (SSD) at 0??? https://www.dropbox.com/s/wtftidndes5qv1a/2016-02-10%20%281%29.png?dl=0 – César Arquero Cabral Feb 10 '16 at 12:17
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    Same problem here using the Clip tool on a OSM-Road Shapefile (downloaded from Geofabrik). New Core i7 Machine (4Ghz) and 16GB DDR4 RAM plus m.2 SSD so it can't be hardware. When I try to clip the road shapefile with the border shapefile of the federal state (Saxony) it takes ages for the processing to run. 10 Minutes for 6% or so and CPU usage only shows around 20 to 30%. Where is the problem? QGIS 2.14.1 – Phil Mar 14 '16 at 17:54
  • If the problem is a bug, maybe you should update to a more recent version of QGIS instead of asking for it to be fixed in the rather old versions you're trying to use. – csk Feb 13 '18 at 18:09
  • Try again with QGIS 3.0, there has been a lot of effort going into making processing algs more performant and making processing in general run in a separate thread. – Matthias Kuhn Feb 26 '18 at 12:15
  • Have a try changing the way the data is stored. If your data is stored in shapefiles, try putting them in a geodatabase instead. Maybe the way the data is accessed makes a difference depending on the software. – gisnside Feb 26 '18 at 08:40

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