
Originally Posted by
Soukyuu
Zakarn, P2P is used for files downloading (in FFXIV's case, it used to be patches), it has nothing to do with server communication, since for P2P you don't really have a server (except for getting the peer lists). In any case, even if your ISP blocks/throttles P2P, it won't lag you. Reading the post you linked, I'm really doubting that's really what's happening.
At least it's not the whole picture, since I am getting lag yet my ISP doesn't throttle P2P as I have no typical symptoms - my µtorrent is always at peak speeds if the swarm can serve it.
What does lag you is running P2P programs parallel to the game, since EU countries still use a lot of asynchronous connections, for example ADSL where the upload bandwidth is fairly limited compared to download bandwidth, and since each packet has to be confirmed with an ACK packet, it can happen that your upload is completely clogged with ACK sends, leaving no room for your FFXIV client's packets telling server what you are doing.
So you can at least ease the lag to some amount if you (and other people at your place) stop down/uploading stuff while you're playing. Don't forget that opening a page with a lot of content (images, gifs) counts as much as streaming a video stream, especially with the "continuous load" most image sites employ nowadays.