I have 10Mbps WAN link speed and with no qos and very light traffic, both FTP and TFTP image upgrade are very slow. I am getting speeds of only 55Kbytes/sec and 50Kbytes/sec respectively. I thought FTP will be much faster (even with 12 bytes per packet more overahead) than TFTP, because of no small 512KB packets used by TFTP and ack requirements for each packet transmitted, but speed seems almost same in both cases.
I am using tftpd32 (recommended by Cisco in so many docs) for TFTP server and FTPDMIN and FreeFTPd and results are similar. Is it limitation of Cisco routers / switches that you can not have faster than 50 to 55Kbytes ( less than 500kbps) for IOS upgrades?