Cygwin itself is a huge mess and a big compatibility problem, and it's not really fair to blame those issues on any particular software distributed by Cygwin.

Cygwin itself is a huge mess and a big compatibility problem, and it's not really fair to blame those issues on any particular software distributed by Cygwin. Emacs has a perfectly good native Windows build available on its download page, and it works great and it supports Slime just fine.