Hi All, Have you considered modifying BOOST_ASSERT to use __assume on MSVC? Briefly speaking __assume(expr) is a hint for optimizer that 'expr' evaluates to nonzero. It can help optimize the code. Standalone use of __assume is not recommended because compiler does not check if the assumption is correct, and if it isn't the program is ill formed. But it fits perfectly in ASSERT macro. This way putting many ASSERTs will not only help to verify the code - it will also help the optimizer. Wow! To be sure I did a small test with MSVC: int f(int n) { // __assume(n == 0); if (n == 1) return 1; else return 0; } produces: xor eax, eax cmp DWORD PTR _n$[esp-4], 1 sete al ret 0 with __assume uncommented: xor eax, eax ret 0 And the comparison is gone. Microsoft docs for __assume are here: http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vccelng/htm... cheers, Marcin