Opencv 3.0 + visual studio 2013 + CUDA + CMake

I've successfully compiled OpenCV 3.0 with CUDA 7 with Visual Studio 2013 makeing the solution with CMake for x64 architecture. I've notice that my *300.dll performances are slower than the already compiled *249.dll for x86 architecture (downloaded from opencv.org). For example the same sobel test program run with 2.4.9 at 30msec while run with 3.0 at 280msec O_O. How could it be possible? Have I missing some optimization or building options? Thats my Flag for Release: //Flags used by the compiler during release builds. CMAKE_C_FLAGS_RELEASE:STRING=/MD /O2 /Ob2 /D NDEBUG