Revert "Increase max pool size again."
Revert "Increase max pool size again."

This reverts commit 280afa4244d5722eb8a33d6637aab53160e47ada.

tomhughes/tilelive-mapnik,mapbox/tilelive-mapnik,CartoDB/tilelive-mapnik,wsw0108/tilesource-mapnik,dshorthouse/tilelive-mapnik