Just as a reference point, I didn't see any measurable slowdown on mkfile (New-Item) throughput on Windows 10 after applying the patch. I suspect this may be more of a filesystem issue.

I also tried this:

    $f = new-object System.IO.FileStream c:\temp\test.dat Create, ReadWrite
    $f.SetLength(8GB)
    $f.Close()

with no speed difference on a patched and unpached system