Konqueror transfer speed drops

I'm transferring large files across the inet using Konqueror and it's working great except that the speed always seems to drop after about 6 or 7 megabytes have been transferred. It drops to less than a quarter of what it was at the beginning of the transfer. The original speed is about what I would expect but then I always get the annoying speed drop.

I'm going from cable to DSL and it starts at around 190 KB/s and drops to about 40KB/s for the duration of the transfer. Does anyone know what causes this and how to sustain normal speeds for the duration of a transfer? Are process priorities getting changed automatically somehow?

Is Konqueror the only program that you have used to do this?
If not, what happened with the others?

I suspect that your ISP is throttling you back when it becomes evident
that you intend to send large a large number of ones and/or zeroes.