How many Feature layers do you have in your Experience?
Well we know that actually it's in map but how many you have and the Experience working smooth?
We have 100 layers that we put in groups, the performance was poor.
We were lowered to 50 little bit better but still when Identify or Drawing it works very very very slow.
So How many feature layers it's make sense, Given the fact that the layers are within groups?
Umm.... 100 layers, grouped or not, in a map, is going to be slow. If it were me, I'd be thinking about what "message" you were trying to share and how to make it accessible, thus improving performance.
I've a few experiences with at least 20 Feature Services embedded, multiple layers, and views along with 16 embedded dashboards, each with multiple tabs. Performance is as expected, given the load times of dashboards. eg; IoT Exp West Highland Way
It really depends, too, on how and where the layers are being used in your Experience. If you go to the Data tab of the Experience Builder, you can see an overview of which layers of a map/service are in use, and by how many widgets.
I could have a map with 100 layers in it, but if none of those layers are used in another widget and the map is in a section with "lazy loading" enabled, I really won't see much of a hit to performance.