The one thing flawed is that many isps give you a very small upload pipe compared to your download
All fine and dandy they say you have 100GBps down, if your upload is only 100KBps
Depending on your ratio its even possible that your upload limit might make almost impossible to actually reach your download speeds. With the way tcp works, you have to ack back during your download. So at some point your upload pipe will be maxed out, and you can not send acks any faster.. Even though it might be possible to download faster per your stated speeds.
This issue you have just recently discovered
Is why so many users ask why does p2p slow down my browsing! Because they never bother to correctly setup their clients to leave some room on their upload side for stuff like dns, or http requests to neowin saying you want to view this url, etc.
If you correctly setup your p2p to use only a % of your upload bandwidth, and not the whole thing - then its possible to continue browsing, emailing, ftping, etc. etc. without any issues - because its still possible for you to ask dns where www.something.tld is or send that request to neowin http server for the next page of the forum section your reading, etc. Or to send to google that you would like to search for whatyamacallits
If you want to fully use your upload pipe sending bits of something to the swarm members, or sending your latest cat video to youtube then you could setup some QoS on your router that says hey I know your queue is full of sending out p2p stuff, but I have this dns request I would like to send right now - please let it cut in line. In simple terms that is what QoS (quality of service) is -- the ability to cut in line, and create different lines (queues) for different protocols. Kind of like fast pass at the amusement park