when working with very large vector or raster files then it can often take some time for the rendering process – and that’s usually annoying!
So, here are some tips for you, how to speed up your QGIS.
1. Enable multi-threaded rendering:
Modern CPUs are multi-core processors. QGIS uses by default only one CPU core for rendering, but you can change this.
Go to Settings -> Options -> Rendering and activate Render layers in parallel using many CPU cores
Multi-threaded rendering should speed up your performance significantly!
Render caching and Feature simplification should be activated by default. Keep this settings.
You can uncheck the less jagged lines option. This will give you less rendering quality, but a little bit of performance
2. Large vector data sets:
Go to Layer Properties -> General -> Create Spatial Index
When working with vector files >500MB I recommend you to work with information stored in a database instead if ESRI Shape files.
This can speed up your performance dramatically (if the connection to your database is fast enough!).
If you want to know how to set up a local database, check out my guide to PostGIS on Linux: part 1 and part 2.
3. Large raster data sets:
Go to Layer Properties -> Pyramids , select the resolutions you want and use Build pyramids.
Pyramids are lower resolution copies of your file depending on the zoom level of your data view.
Usually pyramids are stored outside your raster file in a separate .ovr file. This uses up some disk space, but speeds up your rendering performance dramatically.
If you have any further information for me, how to speed up QGIS: Please let me know in the comments!