I see that this library you are referencing too is in pre-alpha.
So might not be too stable. But thanks for pointing this out!
Freaking sweet!
In my company where I work I had the same issue, we in some cases had to display almost 1.2 mil records.
This would simply break it, so what I made was the window of the leaflet the filter and built some validations on that. We only had specific things we could show on the 'global map'.
This was acceptable as looking at the thing in the entire view wasn't really helpful to us.
The stuff of value is on the detailed levels typically, for our use case.
Another approach we wanted to look at is doing a very basic kmeans clustering based on the view/zoom, and in that way we could condense the data. So cluster the clusters so to speak.
Hope it helps!
Vick