Where is the speed cut in Windows 2008r2?

Question

Server optimization

I installed an optical network card and a 10Gb / s switch, I start measuring with iperf and get this picture

Network load jumps within 20-25%
Who is blocking?

Answer 1

QoS

Answer 2

If you copy to a disk, the disk can block. If you are copying a la from a remote /dev/zero to a local /dev/null, an unloaded TCP Checksum or a similar setting may block, i.e. you can hit the processor.