I am on PN Extra which is an upto 20meg product - the same as the O2 (LLU) product I was on
I am not aware of any traffic management by either O2 or PN that would adversely effect a HTTP download from www.softpedia.com
yet on O2 I could get upto 1mB/s and on PN it was approx 200kB/s.
My house wiring is the same, the line to the exchange is the same, the router is the same. The only things that I can think of that are different are the VPI/VCI settings and the ISP.
Concentrating on the download speeds with O2 it was approx 12716 Kbps downstream and on PN it is approx 10221 Kbps downstream so that is the same as 2 20cm pipes one with 12716 litres of water per hour flowing through it and one with 10221 litres of water per hour - not wildly different! The problem is that is that the O2 pipe gave me 1000 litres in an hour while the PN pipe only gave me 200 litres in an hour.
I have downloaded quite a few VirtualBox updates from FileHippo recently so, similiar sized downloads from the same servers although at different times of the day - possibly all around the same time, with O2 it was fast, with PN it chugs along.