I noticed that mkgmap does not intern any strings. In particular, this tile, generated by the splitter, fails to build with -Xmx3000m on 64-bit jdk under linux. With my patch, mkgmap generates the tile with -Xmx1000m. <bounds minlat='55.1953125' minlon='9.4921875' maxlat='56.6015625' maxlon='11.513671875'/> This tile has 1m nodes. Among the nodes and ways on this tile, there are 12m tags, yet only 100k distinct tag key/value pairs; on average each value occurs 120 times. I explicitly do not use normal string interning because String.intern() strings are kept forever, and I want these strings to be GC'able after the tile is done. I trade GCability for having the occasional string duplicated in memory by flushing the interning table every 10k unique strings. This code is not presently multithread safe; Ideally there should be one string interning table for each parser/thread. Scott