Line Simplification
http://bost.ocks.org/mike/simplify
To simplify geometry to suit the displayed resolution, various line simplification algorithms exist. While Douglas–Peucker is the most well-known, Visvalingam’s algorithm may be more effective and has a remarkably intuitive explanation: it progressively removes points with the least-perceptible change. Amazingly, simplification often allows the elimination of 95% or more points while retaining sufficient detail for visualization. For example, the GeoJSON file used to draw the continental United States above can be reduced from 531KB to 27KB with only minor visual changes.