Hello, I've probably encountered a performance issue with the Layer List widget in api version 4.16+ (version 4.15 and below is fine). After a research, I came to the conclusion that the render method of the widget is called too often, so there is a drastic slowdown of the view (lagging, long rendering time, almost 1000ms). In the Layer List sample on your site everything works fine. I use 10 or more widgets and about 10 layers in the map application, can it be related to that?
I'm just testing that now. It definitely cuts down on the number of requests and the issue with the issue with the listItemCreatedFunction. I think it is a big improvement. I'm still trouble shooting some issues with the layer list and performance but I think this helps.
It appears this solution is no longer working in the latest release