c# too slow for math algos compared to c++ - can i implement asm or c++ code in c# forms? (like c++ lets you have __asm{ })

Question

is there a way to speed up the math process of c#? i know c++ and asm are very quick at math algos but c# takes for ever (like hashing files). i know in c++ you could write __asm { mov eax,12345678 } and so on but is there a way in c# to do that or is it all in this slow ms intermediate language...