I am not sure if this is the right place to ask, so feel free to redirect me if you have a better address.
The "Arch Linux Netboot Live System"  allows to boot Arch Linux install media directly from internet. At the moment the iPXE image chainloads a syslinux image providing a graphical menu. The culprit is loading kernel and initramfs from WAN - tftp is horribly slow if latency increases.
My suggestion is to drop syslinux completely and just use iPXE. Latest development releases from git do have a menu system  and iPXE itself is capable of loading kernel and initramfs via http (or https or whatever you prefer), decreasing boot time dramatically. The only drawback is that iPXE does not have a graphical menu interface... But who cares - it just has to work reliably, no? ;)
Let me know if you need help implementing this or if you are need any more information.