Maps: Determine if limit/lag is from mapbox or from our system

So we currently have a marker limit of 2000 before truncating results. After that 2000 amount the website begins to get slow and laggy though the map does load it becomes hard to zoom in and out and interact with. We should determine if that is from our code, the mapbox code, or possibly both.

Reproduce the map with more than 2,000 markers and compare interaction when zooming and panning. Determine whether the lag comes from the website, Mapbox, or both, then document the responsible component and a verified direction for reducing the slowdown.

Written by the indexing model from the issue text.