Version 5 (modified by johnnyg, 11 years ago) (diff)

added note about KB/s

Bandwidth Tweaking

The settings below are suggestions. They are intended to give users more guidance than the settings recommended in the FAQ, but are by no means definitive.

The best rule to remember is: Don't be greedy. There's more content out there than you can ever consume. You don't need to download it all right now! By allocating your bandwidth properly you can maintain a solid, thick stream of data that fills up your hard-drive 10-times faster than you'd expect. Maximizing your peak download rates can be fun and all, but it doesn't necessarily get you the best over-all performance.

So, as a subsidiary rule, there's this: More is not always better. It rarely works to just crank everything to 11. So, while the settings suggested below may seem low, they should give better results over time.

Determine Internet Connection Speed

Go to to test your connection. It's best to do this with all other applications, including Deluge, closed. You also should run the test a few times, hours or days apart, to make sure your initial results were accurate. by default will give you results in Mbps (Mb/s). To see the results in KB/s (which is what deluge's preferences uses):

  1. Click on "Settings", located in the top left corner of the page
  2. Select "kilobytes" under "Speed Measurement"
  3. Click "Save"

Preferences: Bandwidth

Global Settings

Maximum Connections 250 (You may never see this many connections depending on your per-torrent and active-torrent limits.)
Maximum Upload Slots -1 (Let the per-torrent and active-torrent settings limit this.)
Maximum Download Speed 80 - 95% of tested download speed (Be careful of setting this too high--it can strangle your browsing, media streaming, etc. and other people who use your connection.)
Maximum Upload Speed 80% of tested upload speed (Upload speed is the limiter for most p2p applications.)
Maximum Half-Open Connections: 50 - 100 (Unless you've got a Windows install with limited half-open connections. Then this should be 50 - 80% of that limit.)

Everyone got all excited when it was discovered that Microsoft had, at one point, limited half-open connections in XP and Vista to small numbers. As a plethora of hacks came out to remove this limit, somehow "half-open connections" became the scape-goat for slow download speeds. Suddenly it became de riguer to advise Windows users to hack the TCP/IP driver and set their half-open connections to something huge, like 200.

Most users have no need for a setting that high, and Microsoft has removed the original limit in later releases/patches--or at least made it user-adjustable. Half-open connections should--rapidly--resolve to fully-opened connections or be timed-out. So, you really don't need to allow that many of them to be hanging around.

Maximum Connection Attempts
per Second
20 (When you set your per-torrent connections and such to a reasonable number,
you will fairly quickly establish reliable connections with plenty of peers.
You shouldn't need to be banging around for thousands of new connections every minute.)

Per Torrent Settings

For upload speeds of: < 50 KiB/s 50 - 150 KiB/s 150 - 250 KiB/s > 250 KiB/s
Maximum Connections 30 50 80 120
Maximum Upload Slots 4 5 7 8

While a basic premise of bit-torrenting is a big-ol' "swarm" of peers, you, as a single client, can spread yourself too thin. You're more helpful to the swarm by feeding a limited number of peers with a steady, thnick stream of data, than you are by spraying out droplets of data to a huge number of peers.

So, you should limit your upload slots based on your upload speeds to make sure that each connected peer is getting a reasonable amount of bandwidth.

You should limit your number of connections because it take resources to keep track of each connection, and why track connections that are giving you a trickle if any data? One peer feeding you 5 KiB/s is worth 50 peers flickering at 0.1 KiB/s. Similarly, you don't want/need to be keeping track of a large number of peers waiting around hoping one of your upload slots comes free.

Maximum Download Speed -1 (Let the per-torrent speed by limited by the global settings.)
Maximum Upload Speed -1 (Let the per-torrent speed by limited by the global settings.)

You can, by setting the per-torrent maximums to less than the global maximums, prevent a single torrent from using up all the allocated bandwidth and forcing all of the other (auto-managed) torrents to pause. But there is no advantage to increasing your number of active torrents. Indeed, by letting the torrent with the best speeds dominate, it will finish as quickly as possible and then stop competing for resources with the other torrents in the queue.

Preferences: Queue

Active Torrents

For upload speeds of: < 50 KiB/s 50 - 150 KiB/s 150 - 250 KiB/s > 250 KiB/s
Total active 3 5 10 15
Total active downloading 3 4 8 10
Total active seeding: 3 5 10 15

By setting "active downloading" less than the "total active" you can make sure that you are seeding completed torrents at all times.

Deluge always prioritizes downloads over uploads, so seeding can be set the same as total but all of your downloading slots will still get used.

Note: All downloading torrents are automatically also seeding.

Example Results

Assumed upload speed (KiB/s) 25 50 150 250
Total active torrents 3 5 10 15
Maximum upload slots per torrent 4 5 7 8
Maximum total upload slots 12 25 70 120
Worst-case KiB/s per upload slot 2.1 2.0 2.1 2.1
Worst-case KiB/s per torrent 8.3 10 15 17