I am using QGIS 2.12.0- Lyon (64-bit) at work and have been finding with especially large amounts of data (many vector layers) that all processes on the system have been running slower. I am running on a Windows 7 machine, 64-bit system, with 4GB RAM and an Intel(R) Core i5 processor, at 3.20GHz. I was wondering if increasing the RAM would make a difference to the speed of loading and manipulating my map on QGIS? Is it worth increasing?

I had also heard that ArcGIS versions before 10 were not able to use multi-core processing, and wondered if this may be the case for QGIS also, therefore there is no need to upgrade processors?

  • Are you running a 64 bit version of QGIS?
    – nmtoken
    Apr 14, 2016 at 13:39
  • 1
    Depends how big your map is, what other apps you are running, I would think. Generally speaking, RAM increases performance, whether the underlying software can benefit from multi-core processing or not. Certain things are not amenable to parallel processing, but everything suffers from lack of RAM. Apr 14, 2016 at 13:42
  • The multiprocessing support reference to ArcGIS is incorrect. Esri has always supported multiprocessing (I've been doing so since Arc/Info 4.02); 10.x made it possible to optionally submit geoprocessing jobs in the background from within the UI. 4Gb RAM is just barely enough for Microsoft Windows 7. My kids' computer has 8Gb, and my personal computer has 16Gb (which I may double to 32Gb for $100). Tasks which are I/O bound will not likely see benefit from additional RAM.
    – Vince
    Apr 14, 2016 at 13:59
  • Another idea might be to check if your data is in the same coordinate reference. If not you can consider reprojecting it to the same. Because when Qgis draws your features on the map it is reprojecting ALL visible objects on-the-fly that are not in the same CRS before showing them. That may save some miliseconds...
    – Matte
    Apr 15, 2016 at 5:40

2 Answers 2


Loading in the first place depends a lot on the HDD/SSD and not the RAM.

Drawing depends a lot on your CPU or Graphic-Card, which is done after loading or manipulating something in the map (like zoom or pan).

Qgis can be set to use multiple cores to draw features. This you can find in the Options. Maybe its faster then.

Then you can just open the task-manager and look how much RAM is used. If it is not 3/4 full its just slow because of the drawing of the vector data. More RAM will not much fasten up that specific issue.

If the RAM is full it will be extremly slow as it starts to swap to HDD. You will notice it as the whole system feels like it is hung up for some seconds from time to time.

Otherwise increasing RAM is cheap and always good as Vince mentioned, but maybe not the issue here.

  • 4GB is probably the problem: that's barely enough to run Firefox by itself, these days. The SSD/HDD issue is critical if the data has a lot of features and is being loaded out of a DB (e.g., PostGIS). My workflow is no big deal, but it routinely has several layers each with either 100k+ features, or features with large numbers of vertices (40,000-odd for one planning overlay). I moved our PostGIS vector database (~280GB) from an internal 4TB HDD onto an internal 1TB SSD. It made a significant difference (already had plenty of RAM).
    – GT.
    May 19, 2017 at 3:07

Memory upgrades are always good, especially in a 64 bit system. 4GB on a 64 bit system leaves a lot to be desired.

I would also clear out my temp folder, and any unnecessary files frequently. (I am really old school about this, I do this at least twice a week.)

Your video processor will have a great deal (almost everything) to do with rendering speed, and to be honest, I do not know if QGIS takes advantage of multi-core video processors such as the Cuda cards from NVIDIA. If it is able to, then there is probably a setting that needs to looked into to increase that performance. I have never experimented with that.

A clean hard drive, with a lot of free space helps if files are being written to the drive, and a Solid State drive with the faster read/write speeds will definitely improve loading times.

Turn off as many processes as you can while using any processing intensive software, and you will see improvements in performance.

Some Anti-Virus software will slow performance considerably, but I will not point any fingers. You may want to disable the software to see if you see any improvements. (Run a scan first!, then disconnect from the internet.)

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