In many ways, WSL is the Cygwin concept implemented inside the system layer. Where Cygwin reimplements things in Win32-compatible-ish code and then calls that c

In many ways, WSL is the Cygwin concept implemented inside the system layer. Where Cygwin reimplements things in Win32-compatible-ish code and then calls that code, WSL translates the calls directly into compatible Windows code. In theory, sometimes this is faster, and sometimes slower. In practice, whereas Cygwin has to jump through hoops to work around incompatible interfaces at the library layer, WSL can get Windows to implement the things they need to optimize the especially painful parts. This is also why file system access is so slow in WSL — the two systems are far enough apart that building such a fast path is either hard or really hard, depending on how much compatibility is important to you.