What will happen when the load increases

I am creating a real estate search startup. I connect the OpenStreetMap using leaflet.

L.tileLayer('https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png', { attribution: '© OpenStreetMap contributors' }).addTo(map);

I also add a large number of circle-markers to the map

const theMarker = window.L.circle([item.latitude, item.longitude],marker);

So far, everything is working. It's free, am I right? And what will happen when the load increases?