Is there any reasons to not use "mmap" to read files?

[rempas]

On Sunday, 6 February 2022 at 10:53:49 UTC, Temtaime wrote:
> Perso i'm almost always use mmap for opening large files for 
> r/w. It IS faster.
> Exception are small ones that can be read into the memory using 
> std.file.read for example.

Thank you! For how big files are we talking about? Also like 
another guy told me in another (C) forum, "mmap" is for Unix 
systems so do you know if Windows or MacOS can emulate that 
behavior with their memory allocation system calls?