Why is bittorrent slow from the home computer

For how Windows determines internet connectivity, see this SuperUser question. Basically, Windows tries to access a Microsoft hosted text document and judges your connectivity depending on the response (timeout, 403 denied, 200 OK, etc).

Yes, BitTorrent (or anything else) using excessively large chunks of your bandwidth can saturate your connection. Basically, you're transferring so much at once that other packets end up timing out and getting dropped. Imagine a water pipe, if you try to put too much in it will fill up faster than it can be emptied and start overflowing, losing the water that overflows.

A typical IP (Internet Protocol) request requires you to send some packets to the server you are requesting from, which will then send some packets back - its response. This requires both some upstream and downstream bandwidth. When your upstream bandwidth becomes saturated, you can't send the request. When your downstream bandwidth becomes saturated, you can't receive the response. It is entirely possible for a BitTorrent client to use all your available bandwidth.

Generally, it is best to set your BitTorrent client to only utilise up to 80% of your upstream and downstream bandwidth, as determined by speed tests. If you require low latency, e.g. online gaming, the percentage should be even lower.

It's also possible for BitTorrent to overload home modems and routers by opening too many connections, overflowing their NAT tables. The maximum number of connections should therefore be kept at a fairly low level. A maximum of 300 connections globally should be alright. An overflowing NAT table's symptoms will vary from router to router, but often cause them to freeze.

It sounds like that torrent has poor sources.

When you download a torrent, you need to make sure that it has sufficient sources available. There are two kinds of sources that a torrent can have in its swarm:

• Seeds - People who have the entire torrent (the whole file/all files)
• Peers - People who have none or some of the torrent

In addition, different parts of the file(s) will usually be distributed in a way to maximize the availability, so that even if there are few or even no seeds, then the whole torrent could still be gotten if all of its pieces are available somewhere in the swarm.

Select the torrent then look at the following areas of the details pane and/or the torrent’s columns in the list. To get the whole thing, you need to make sure that either there is at least one seed or that the availability is greater than or equal to 1.0. Of course, the higher the number of seeds and availability, the better because there are more sources that you can download from, so it will complete faster.