QGIS » QGIS Application

When you have several layers in a GIS project and then you move to the map composer and you want to create a legend it takes a lot of time. Example: I'm working with around 50 layers (not very complex layers) and when you create the legend you have to wait around 5 minutes till all the layers are showed in the legend. Then, if you move the legend or modify the layers showed in the legend it also takes a lot of time

Cesar Herrera wrote:

When you have several layers in a GIS project and then you move to the map composer and you want to create a legend it takes a lot of time. Example: I'm working with around 50 layers (not very complex layers) and when you create the legend you have to wait around 5 minutes till all the layers are showed in the legend. Then, if you move the legend or modify the layers showed in the legend it also takes a lot of time

can you possibly attach/link a sample project with data?

I think I can support this. We have hundreds of layers in our GIS. I just tried adding a legend with the Add Legend tool, and it took a long time to appear. Then, with the legend visible in the layout, the whole application is very slow to respond to any command, so bad, in fact, that I think I may have to terminate the application from Windows.

I never liked that the legend appears with all layers already in it, so we add legends from a set of Legend .qpt templates, formatted for different page sizes, which appear with no layers added, so then we can just add the layers we want.

Because we do it that way, I really like that you can add multiple layers in one command in QGIS 3, because it was always an annoyance to have to add them one-at-a-time in QGIS 2.

I suggest it would be far preferable for the Add Legend tool to create an empty legend by default, or maybe in the 'New Item Properties' dialog for legends, have three radio button options for the user to choose Add empty legend, Add with visible layers only, or Add with all layers.

Cesar Herrera wrote:

Including a nonreal QGIS project. I adapted some layers and QGZ file in order to reproduce the problem.

I tested on my clean Windows and Linux testing VMs, and add the legend does not take more than 2/3 seconds (which is ok to me considered its size).

I tested on my clean Windows and Linux testing VMs, and add the legend does not take more than 2/3 seconds (which is ok to me considered its size).

can you please test again on the latest versions and on new/clean profile?

I tested using the current versions (not master) of 3.6.1 and 3.4.6. I tried installing the nightly master of 3.4.6, but there seems to be something wrong with the OSGeo4W network installer - failing to copy some essential files or environment path variables or something.

Anyway, for the versions that I tested, using our very large .qgz project the time to add a legend varied between 74 seconds (on Citrix) and 230 seconds (on Windows laptop). Once the legend was completed, then the time taken to respond to a click on another item was between 38 seconds (Citrix) and 70 seconds (laptop).

You would probably agree that these are not okay performances.

Steve Lowman wrote:

I tested using the current versions (not master) of 3.6.1 and 3.4.6. I tried installing the nightly master of 3.4.6, but there seems to be something wrong with the OSGeo4W network installer - failing to copy some essential files or environment path variables or something.

Anyway, for the versions that I tested, using our very large .qgz project the time to add a legend varied between 74 seconds (on Citrix) and 230 seconds (on Windows laptop). Once the legend was completed, then the time taken to respond to a click on another item was between 38 seconds (Citrix) and 70 seconds (laptop).

You would probably agree that these are not okay performances.

can you add/link such project?

Hi. Sorry, I can't do that. Our project has far too many layers, and many of them are subject to copyrights.

I also just tested using Cesar's project and layers. The legend loading and other performance timings were okay with that one, so it does not reproduce the problem that you get with a lot more layers.

Steve Lowman wrote:

Hi. Sorry, I can't do that. Our project has far too many layers, and many of them are subject to copyrights.

can you say if with the same type of project things were better in 2.18?

I just tested the same project in 2.18, and the Add Legend tool worked fine rendering the legend with all the layers listed almost instantly, and then no delay in selecting a different item.

I also tested a .qgs project in 3.4, and I can confirm the problem occurs in 3.4 for both .qgz and .qgs projects.

It was a slightly better performance for the .qgs project, taking approx 60 seconds to add the legend and then 30 seconds to select a different item, but I only tested it once, so the small difference compared to last week's test of the same project as .qgz might have been for no particular reason.