title: Tilemill taking a long time to export to mbtiles
body: <p>I have a map with a lot of points (60k). They're spread across 21 separate layers. (It's a demographic scatterplot map.)</p>
  
  <p>I'm exporting to mbtiles with a zoom range of 11-15. The geographic area is around 700 square miles. </p>
  
  <p>I'm only exporting the points, not any underlying basemap. Supposedly, this should only generate a 1-10mb file. But I'm getting a half-hour wait to bake the tiles.</p>
  
  <p>Is that unusual?</p>