[Bug]: Map loading very long after upgrading to LWC 3.7

[SecondGIS]

What is the bug? (in English)

Hi there,
I was running Lizmap Web Client 3.6.12 with a few maps based on PostgreSQL / PostGIS layers, which was very fine.
Since I got a message in QGis Lizmap plugin saying version 3.6 is deprecated I decided to upgrade to LizMap Web Client version 3.7.10 (upgrading lizmap_server plugin too to version 2.10.0).
Since then my maps are incredibly long to load : 30 seconds at least, when it was only a few seconds with previous version I haven't modified my maps or any other software component in between.
When I load one of maps, I got the LizMap logo for 1 / 2s, then the empty map frame is displayed, with the legend panel taking, as said, like 30s to be displayed, and only then my map layer are visible.

Steps to reproduce the issue

1 - Publish a map with PostGis layers with LWC 3.6 and make sure that it is displayed correctly and fast enough in your web browser ;
2 - Upgrade Lizmap Web Client to version 3.7.10 (and lizmap_server plugin to version 2.10.0 or 2.9.4 as well)
3 - Try to load the same map in your web browser

Versions, safeguards, check summary etc

Versions :

• Lizmap Web Client : 3.7.10
• Lizmap plugin : 4.3.24
• QGIS Desktop : 3.28.15
• QGIS Server : 3.28.13
• Py-QGIS-Server : 1.8.8
• QGIS Server plugin atlasprint : 3.3.2
• QGIS Server plugin lizmap_server : 2.10.0
• QGIS Server plugin wfsOutputExtension : 1.8.0

List of safeguards :

• Mode : normal
• Allow parent folder : no
• Prevent other drive : yes
• Prevent PG service : yes
• Prevent PG Auth DB : yes
• Force PG user&pass : yes
• Prevent ECW : yes

Check Lizmap plugin

• I have done the step just before in the Lizmap QGIS desktop plugin before opening this ticket. Otherwise, my ticket is not considered valid and might get closed.

Operating system

ubuntu 22.04

Browsers

Firefox

Browsers version

Firefox 130.0, Chromium 128.0

Relevant log output

No response

[Gustry]

Unfortunately, without more info, you will need to debug where the bottleneck is. It really depends on your project.

Please open your "Developper tools" (F12), to see HTTP requests and check which ones are too long.

Maybe linked to #4521 about the legend, or maybe another bottleneck.

[SecondGIS]

You can follow further debugging and discussion about this issue at #4521.

[github-actions]

This issue is missing some feedbacks. 👻
Please have a look to the discussion, thanks. 🦎

[r9zzai]

Anyone can confirm that "getProjectConfig" request increased loading time since lwc 3.7.x (tested multiple projects, but one with 5 sec for 4 local file layers)? We had similar expierence (but not related to given link i think - getlegendimage request) and staid on lwc 3.6.x because of that.

Tested:
Lwc 3.8.3, qgis 3.38.3
Lwc 3.8.3 qgis 3.34.3
Lwc 3.6.x tested up to 3.7.x qgis 3.34.3

Curr. Setting:
Lwc 3.6.14 qgis 3.28.15

[github-actions]

This issue is missing some feedbacks. 👻
Please have a look to the discussion, thanks. 🦎