Using sanboot --no-describe to boot iso image is extremely slow compare to memdisk

[robinsmidsrod]

The only thing I can think of is that your web server doesn't support keep-alive or range-requests, which cause it to download the entire ISO every time it tries to access some part of it when using sanboot. But since your trying to boot WinPE, why aren't you using wimboot? There is a WinPE-specific howto here: http://ipxe.org/howto/winpe