Description

I belive the currently php-src impl. checks if any iterated item has children on each RecursiveDirectoryIterator::hasChildren call. This is slow.

I propose to reuse current item file entry file flag (d_type = DT_REG on linux, dwFileAttributes on Windows). If a current item is a file, it cannot have children and it will optimize typical usecase - directory with many regular files.

repro iterator code:

$iter = new RecursiveDirectoryIterator(
    $path,
    \RecursiveDirectoryIterator::SKIP_DOTS | \RecursiveDirectoryIterator::FOLLOW_SYMLINKS
);

Measured on Windows, maybe on linux it is faster.