Hi Tim, Attached is a performance test that tries to immitate the priority_queue usage a fast marching algorithm. I actually wrote this performance test in 2005 while tuning a heap implementation (TSequentialHeap, not attached) used by a "real" fast marching algorithm. I tried to adapt this test for Boost.Heap now, but it looks like I haven't yet found out how to use the mutable heap interface optimally for this task. The most obvious symptom of this are the performance numbers I get when executing the performance test: $ g++ heaptest.cpp -O2 -DNDEBUG -Iboost_heap-449f378 -I/cygdrive/c/nobackup/boost_release -DHAVE_SEQ_HEAP $ ./a.exe Sanity Check Small TStaticHeap Test : passed Linear TStaticHeap Test : passed March TStaticHeap Test : passed Small TUglyHeap Test : passed Linear TUglyHeap Test : passed Small TSequentialHeap Test : passed Linear TSequentialHeap Test : passed March TSequentialHeap Test : passed Small b_heap Test : passed Linear b_heap Test : passed March b_heap Test : passed Small binomial_heap Test : passed Linear binomial_heap Test : passed March binomial_heap Test : passed Small d_ary_heap Test : passed Linear d_ary_heap Test : passed March d_ary_heap Test : passed Small fibonacci_heap Test : passed Linear fibonacci_heap Test : passed March fibonacci_heap Test : passed Performance Check for Linear Forward 297 ticks and 15952569 compares for TStaticHeap 296 ticks and 15952569 compares for TStaticHeap 95 ticks and 5495826 compares for TSequentialHeap 78 ticks and 5495826 compares for TSequentialHeap 999 ticks and 20929621 compares for b_heap 1032 ticks and 20929621 compares for b_heap 875 ticks and 7012461 compares for binomial_heap 906 ticks and 7012461 compares for binomial_heap 797 ticks and 16164008 compares for d_ary_heap 812 ticks and 16164008 compares for d_ary_heap 688 ticks and 5637046 compares for fibonacci_heap 688 ticks and 5637046 compares for fibonacci_heap Performance Check for Linear Backward 297 ticks and 22976046 compares for TStaticHeap 328 ticks and 22976046 compares for TStaticHeap 94 ticks and 5225203 compares for TSequentialHeap 93 ticks and 5225203 compares for TSequentialHeap 1125 ticks and 31971032 compares for b_heap 1125 ticks and 31971032 compares for b_heap 688 ticks and 5636875 compares for binomial_heap 718 ticks and 5636875 compares for binomial_heap 813 ticks and 19465560 compares for d_ary_heap 828 ticks and 19465560 compares for d_ary_heap 703 ticks and 5866500 compares for fibonacci_heap 703 ticks and 5866500 compares for fibonacci_heap Performance Check for March 1672 ticks and 93489201 compares for TStaticHeap 1734 ticks and 93489201 compares for TStaticHeap 921 ticks and 53507489 compares for TSequentialHeap 907 ticks and 53507489 compares for TSequentialHeap 5625 ticks and 121120384 compares for b_heap 5563 ticks and 121120384 compares for b_heap 6312 ticks and 73639894 compares for binomial_heap 6265 ticks and 73639894 compares for binomial_heap 4391 ticks and 92667621 compares for d_ary_heap 4375 ticks and 92667621 compares for d_ary_heap 4000 ticks and 39902719 compares for fibonacci_heap 4078 ticks and 39902719 compares for fibonacci_heap $ We can see that "fibonacci_heap" has always more than a factor two fewer comparisons than TStaticHeap (a simple text book binary heap implementation used as reference), but is always more than a factor two slower than TStaticHeap. And "fibonacci_heap" seems to be the fastest heap from Boost.Heap in this performance test, while TStaticHeap is still a factor two slower than the tuned TSequentialHeap. I guess the problem here is that I found no way around using "std::pair<value_type, value_type*>" as value_type for the heap, because I need to know the position in the bulk of the point with the smallest arrival time. But Dijkstra algorithm should be no different, I have to know the vertex in the graph with the shortest path. Independent of this, I also have a totally different question. There is a FIXME in line 233 of the test program, and if the following line is commented out, fibonacci_heap shows undefined behavior, ranging from segmentation fault to failing the Sanity Check. Here is the code surrounding the FIXME: std::size_t Set_Size ( std::size_t lSize_p) { if (!m_tHeap.empty()) { exit(1); } // FIXME: I don't understand why the fibonacci_heap shows undefined behavior if clear() is not called. m_tHeap.clear(); m_tBackpointer.clear(); m_tBackpointer.resize(lSize_p); return lSize_p; } You can see that the heap is actually empty, so why is calling clear() on the empty heap important in case of a fibonacci_heap? Regards, Thomas