erm you expect help? well im gonna need some info...eg an actual problem to overcome, you say you have done all that is said...havew you done it correctly? it takes some fine tuning..and by getting slower and slower, do you mmean it actualy does get slower and slower or its just real slow? because the speed is afected by a few things:

time of day- people with the file have to be online, and the right people
your internet connection
their internet connection (only go for those with full stars of quality)
firewalls
number of people who have the file (time of day)
try it with different files and see what happens

without a proper problem, im afraid i can provide little/no further help