I have been  downloading jpg's via a generated text
file.(www.xxxxx.com/upload/10.jpg, www.xxxxxx.com/upload/11.jpg    etc.  Many
of these are empty, as I am exploring the site.) 

The parsing remained steady for a couple of weeks. But after I tripled my
dl/ul speed with an upgrade, the downloading became erratic,  often hanging 
at  0 for seconds at a time. Consequently exploring a string takes much
longer. 

Any ideas as to what  the problem is, and how to fix it?