Make sure you run outside of the IDE. That is key.
-edit- I LOVE SLaks comment. \"The amount of misinformation in these answers is staggering.\" :D
you are calling static function in c# code which will be inlined, and in c++ you use nonstatic function. i have ~1.4 sec for c++. with g++ -O3 you can have 1.21 sec.
you just can't compare c# with c++ with badly translated code