And as a result of this, if you want to optimize your program to be fast on Windows, you will make very different optimization decisions than on other platforms.

For example, Windows runs virus scans on close(), which makes it very slow. This means that sometimes it makes sense to have one or more background threads exclusively dedicated to closing files.

There's a good talk on this at https://www.youtube.com/watch?v=qbKGw8MQ0i8