multi_array performance

Hi, I am very new in using Boost library. I start replacing row memory array with 'multi_array' class template but the performace slow down a lot. Running this test program... //begin------------------ #include "windows.h" #include <iostream> #include "boost\multi_array.hpp" using namespace std; using namespace boost; int main() { const size_t DimX = 2000; const size_t DimY = 1500; const size_t DimZ = 1; multi_array V3(extents[DimZ][DimY][DimX]); int iVal; unsigned long time1 = GetTickCount(); for (size_t Z=0; Z