Hello, I'm testing same code compiling under MSVC 8.0 or gcc 3.4.2 on the same machine. I face two different problems around boost::dynamic_bitset : - with msvc version : dynamic_bitset allocation is very, very slow (compare to gcc execution time), - with gcc version, it seems (i'm quiete sure) that dynamic_bitset allocation take more and more time after several hours of intensive use. The two problem sound like a problem around dynamic_bitset allocation. Somebody did notice that ? Thanks for your help, Nadine