I knew in theory one can use mmap and unsafe pointer in go. One main different between C and go is this: C can type cast any mmap pointer and de-reference

I knew in theory one can use mmap and unsafe pointer in go. One main different between C and go is this: C can type cast any mmap pointer and de-reference it got the values (pointer, offset to other locations) extremely fast - < 0.01 micro-seconds (assuming page is swap in.) BTW, I do track C line code execute time nano-seconds resolution all the time. It is not difficult to do with RDTSC instruction. It gave you timing resolution in term of CPU clock cycles - 1 2GHz CPU clock cycle = 500 picoseconds, One can easily see the system paging and context switching info from those resolution. In C code, that is only a few assembly instructions. In go (or other GC type language) that one operations is translate to multiple C functions calls. That's probably tens if not at lease hundred times different in pure CPU cycles. When one has to do this hundreds of millions times, that usually makes huge different in overall execution time. I personally know a lot of test cases that means minutes to finished certain operations v.s. days (+GBs of RAM).