Event management is a bottleneck with big datasets

I’m creating a lot of circle markers in a layer using a geoJson of 13000+ features.

L.geoJson(data, {
    pointToLayer: function (feature, latlng) {
        return L.circleMarker(latlng);
    }
}).addTo(map);

this takes about 14 seconds in my browser (it’s OK, it’s a lot of data!). I profiled the CPU to understand what was taking so long, and I found that just this for takes 12 seconds.

https://github.com/Leaflet/Leaflet/blob/a97b87d0333fdc4b0c18d7b2ee9c15b393ae76ff/src/core/Events.js#L110

I think that using a different strategy to store the listeners, we could improve a lot the amount of data that Leaflet is able to insert in an acceptable amount of time.

[IvanSanchez]

Playground with #5054: https://playground-leaflet.rhcloud.com/giw/edit?html,output Time: ~300msec

[perliedman]

Hm, I actually thought I reopened it yesterday, but apparently must have missed the button. Sorry about that.