Currently GeoPointField queries only use the Terms Dictionary for ranges that fall within and on the boundary of the query shape. For boundary ranges the full precision terms are iterated, for within ranges the postings list is used.
Instead of iterating full precision terms for boundary ranges, this enhancement cuts over to DocValues for post-filtering boundary terms. This allows us to increase precisionStep for GeoPointField thereby reducing the number of terms and the size of the index. This enhancement should also provide a boost in query performance since visiting more docs and fewer terms should be more efficient than visiting fewer docs and more terms.