When booting in PXE, a boot image is loaded. This may take several minutes to complete. To reduce the loading time, it is necessary to make a change in the registry.
WDS avec SCCM 2012
When using SCCM 2012 you just have to add the registry key to the site server and restart the WDS service:
Location: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\SMS\DP Name: RamDiskTFTPBlockSize TYPE: REG_DWORD Value: 16384