Torrents are slowing down my Firefox!
June 29, 2008 5:54 AM   Subscribe

Whenever I run Transmission on OSX, my Firefox browsing slows to a trickle, or simply stops altogether.

I have an iMac running OSX 10.5.3, and I use Transmission to download torrents, and less frequently Limewire. About a month ago I moved to a new house and a new ISP, an DSL line with a 4500 kb/s download, and about 800 up (in Tokyo). My download and surfing speeds aren't as fast as my previous place, but it's still quite fast.

Recently, though, whenever I fire up Transmission and/or Limewire, my browsing just stops. Sometimes not completely, but only if whatever I'm downloading is itself just a trickle. (This isn't OS specific: I use BootCamp and have the same problem when booted into Win XP, using uTorrent and FF). The strange thing is this problem just cropped up about a week ago, and surfing while downloading worked fine when I first got the connection going.

I've read some other posts about this problem, but still can't figure it out. I've installed Carrafix, for example, but at least at the time of this writing (and perhaps never), I don't understand it. I'm only moderately computer literate and the whole "bandwidth throttling", "bottlenecking" stuff is new to me.

I don't really know what to do. Others have suggested cfosSpeed, but it's Windows only and I mostly use OSX--is there a Mac equivalent to this program? Any other tricks or suggestions?
posted by zardoz to Computers & Internet (11 answers total) 2 users marked this as a favorite
Have you tried throttling the total upload and download speed (start with 50KB/s for each and then increase to till you see the effect)?

IF it's neither of these, the I'd bet it's to do with the number of connections. Reduce the maximum active connections to 50 or so and then increase that till you see an effect
posted by claudius at 6:00 AM on June 29, 2008

claudius--it happens no matter my up and down speed, or number of connections. I'll fiddle with this some more, though, to be sure.

And FWIW, I can live with slow(ish) torrent downloads, it's the browser crawling to a stop that I really want to fix.
posted by zardoz at 6:12 AM on June 29, 2008

Is there a setting for half-open connections?

Are you running through a (home) router?
posted by claudius at 6:16 AM on June 29, 2008

Does Safari slow down as much? If not, try a different FF version - I heard rumors of a bug where it would fsync() all the time (it would periodically stop and wait for all disk activity in the system to complete; bad idea when the torrent client is *always* writing something)
posted by you at 6:25 AM on June 29, 2008

I don't see anything for half-open connections in the Transmission preferences. I do have an ADSL router here at the house. My ISP is Yahoo, if you can believe that.
posted by zardoz at 6:26 AM on June 29, 2008

Same thing happens in Safari. Actually, now that I think of it, I think this all started when I installed Firefox 3...maybe I should go back to the old version. :(
posted by zardoz at 6:29 AM on June 29, 2008

Does the router have a setting for maxium open connections? For TCP timeout? Can you se them to the maximum and 5 minutes respectively?
posted by claudius at 6:51 AM on June 29, 2008

If you've set a global limit on your torrents, make sure that you haven't set a higher (or unlimited) limit on an individual torrent.

And of course, this might be your ISP slowing you down while you're downloading torrents. If that's the problem, tick both of the "Prefer encrypted peers" and "Ignore unencrypted peers" options in the advanced preferences pane.
posted by robcorr at 6:56 AM on June 29, 2008

Set a lower transfer rate in the Speed Limit mode (Preferences > Bandwidth). I call this the turtle mode. When you want to browse, click on the little turtle at the bottom of the main window.
posted by clearlydemon at 9:40 AM on June 29, 2008

Try dropping the global maximum connections (in the "Peers" tab) steeply to see if you get an improvement. You might be overloading your router.
posted by nathan_teske at 10:01 AM on June 29, 2008

The basic situation is this.

When you connect to download information on the 'net, you send out a request to the computer serving up that information (opening the connection) and their computer sends you the data. Once they're finished, the connection is closed.

Now, when you grab a webpage, you only open a few connections with the webserver, for the pictures, text etc. If the page is http (unencrypted) your ISP can see the connection, and see that it's webtraffic.

Bittorrent opens lots and lots of connections to download small chunks from many different sources. Even if the traffic itself is encrypted, this behaviour is easily spottable by the ISP as torrent traffic with the right equipment.

Here's the difference causes of slowdowns.

1) The bandwidth you're using for torrent traffic, especially uploading the file to other people saturates your upload bandwidth. When you then try to establish your few connections for web servers. They get queued up and either go very slow or timeout altogether. By throttling your upload bandwidth use in the torrent client to well below your actual upload bandwidth (which is much smaller than your download bandwidth, and more easily clogged up), you stop this delaying of outbound web connections. This is the most common cause of torrent traffic crippling web-browsing. Measure your actual upload bandwidth using a web-based speed-tester close to you when not doing anything else, and set your torrent upload cap to at most 80% of your real maximum. Don't forget, KB (kilobytes) are 8 times larger than Kb (kilobits).

2) one other solution to the above is traffic shaping, also known as QoS (quality of service) - cFosSpeed does this on windows to make web-traffic requests higher priority than torrent traffic, so they get put at the front of the queue, so even when there's a big queue web-browsing still goes at full speed. Carrafix is a direct equivalent on OSX. It's not the simplest thing to setup, but it does allow you to prioritise upload traffic to http and https ports (80 and 443 respectively)

3) torrents establish a lot of connections at once. Your router has to keep track of these, and make sure they all go to the right place. Some cheap routers can't handle this, and crash or just stop routing new traffic. If your torrent traffic dies at the same time as web browsing dies, this is a possible cause; if resetting your routers fixes it for a little while, this is very likely your cause. You can usually limit the number of connections made by your torrent client. Depending upon your router, you may need to set this as low as 10 or 20.

4) half-open connections are ones where one side was supposed to be sending data now, but has stopped. They're a bit like zombie connections, and they can contribute to the problem above if you get a lot of them. windows also has a very low tolerance for half-open connections, though I don't think OSX has that problem. You can specify in the OS to allow more or less half-open connections at any given time, to speed up your connection, or prevent your router being overloaded, respectively. It's an advanced tweak that generally makes very little difference.

5) ISP filtering. Your ISP can spot unencrypted torrent traffic very easily, and throttle it (i.e. the reverse of step 2, they deliberately make it slower). Most ISPs do this now, especially the big ones. Encrypted torrent traffic is harder to spot, but still spottable with the right equipment; again, the big ISPs are the worst for this because they can afford it. The throttling might only be against the torrent traffic, or they might just throttle your entire connection, so everything including webtraffic goes slow - pipex started doing this to me before I switched.

Some throttle bittorrent and also have a hard bandwidth cap, sometimes in secret, and throttle all your traffic in peak hours once you go past your cap. I believe the caps are very high in Japan though, in comparison to US and european ISPs.

6) Your browser is broken!

Since you've tried different browsers, we can eliminate 6. Throttle your upload and connections down to absolute tiny levels, i.e. 10kb/s and 5 connections. If it still happens, it's probably not your router or line being overloaded, and thus not 1, 2 or 3. The most likely candidate at that point is your ISP. encrypt your torrent traffic, and see what happens. If it still goes very slowly, then you may need to disguise your traffic even further. The easiest way is a torrent friendly VPN provider. I use relakks, and shortly to be torrentfreedom in europe, both have a cheap one month sub for testing purposes. Best if you can find a japanese one for speed, but if you're worried about snooping on your traffic, one from a non-privacy invading country is best. Sweden (relakks) used to be, but not any longer.

Another option if it is your ISP is to switch to an ISP that doesn't throttle torrent traffic! Check terms and conditions carefully, and look for Fair Use Policies and the like - it's usually in very lawyery language, but it should be in that they do 'traffic management' or 'fair load balancing' or some such bullshit. Non throttling ISPs tend to use it as a selling point these days.
posted by ArkhanJG at 10:11 AM on June 29, 2008 [3 favorites]

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