Hello WanMil, I also thought about reducing the CPU time in LocationHook, but with a different approach: I think a lot of time is used because the quadtree first adds elements to resultList, (a HashSet) and 2nd a loop takes all these elements to add tags. Two ideas: 1) Optimization: It might save time if we could pass a function pointer to the quadtree. The function does the tagging for one element, and we don't have to manage resultlists. I implemented that, but the program was slower. I assume that was caused by the fact that I did not implement the part that removes elements from the quadtree when they were "fully worked out". 2) An completely different approach: I did not yet fully understand the algorithmn in LocationHook, but I got the impression that it might be possible to create a dictionary with combinations of admin-level tags, and save a reference to that dictionary instead of adding similar tags to each element. This could save space and time, but would require additional logic in class Element. Do you think this is worth trying? Ciao, Gerd -- View this message in context: http://gis.638310.n2.nabble.com/PATCH-v1-LocationHook-speedup-tp7135704p7137... Sent from the Mkgmap Development mailing list archive at Nabble.com.