static Map<S, WikiPage> indexedSimpleWikipedia_fast() {
  File f = unpackSimpleWikipedia();
  File cacheFile = getProgramFile(#1008009, "simplewiki-" + fileSize(f) + ".index.gz");
  
  if (fileSize(cacheFile) == 0)
    saveGZStructureToFile(cacheFile, asList(indexSimpleWikipedia()));

  Map<S, IndexedWikiPage> map = ciMap();    
  for (IndexedWikiPage ip : (L<IndexedWikiPage>) unstructureGZFile(cacheFile))
    map.put(ip.title, ip);
  ret indexedSimpleWikipedia_magicMap(map);
}

Began life as a copy of #1014162