As I said in the other thread, in my tests the SD card was the bottleneck. Without the writing to SD card, data is uploaded to the Duet from Chrome at 3Mbytes/sec on my setup.
Questions on the web interface are best addressed to chrishamm, but I'm not sure whether he monitors this particular forum. However, I believe the upload does go as a straight POST - that's what it looks like in Wireshark anyway.
I have been assuming that you are using DuetWebControl 1.08 and either my 1.08r-dc42 firmware or chrishamm's latest firmware. Can you confirm both of those points?
Edited 2 time(s). Last edit at 01/26/2016 07:02PM by dc42.
Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod
Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].