Performance of OS Build through PXE

Hello All,

In our environment we have a PXE server and we deploy the images to the laptops that is booted through Network. The PXE server is built in a dedicated VLAN. It is working properly but too slow. We compared the results with USB using the same image (same amount of applications, drivers etc) and there is a 40 mins difference.
I was thinking that the whole image is sent to the laptop at the initiation and all the later steps are happening on the laptop locally but the results you can see in the table below does not say so.

Can you please help me to understand how the file copy happens between bare metal target and PXE server, how we can increase the performance, any configuration settings we can apply ??

Thanks in advance