One way of solving this issue is serving pre-rendered image tiles rather than overlaying each data point separately: http://blog.cartodb.com/the-versatility-of-retreiving-and-re...

Thanks for the suggestion! We'll certainly look into Freebase. We don't use the google maps API to plot the points, only the map itself. So we don't need limit ourselves to these restrictions. In this case we render the points with SVG, but can also do this with webGL for better performance.