Jump to content

uTorrent downloads slow when in background


Recommended Posts

I have a very, very strange problem. This problem starten when I bought a new computer, installed Windows 8 from scratch and the latest uTorrent.

When I have the uTorrent window in focus the torrent download speed is OK, but if I place it in the background - for instance by browsing in Firefox or working in any other program, the download speed slows down in uTorrent after a few minutes. It slows down, sometimes to only 1/10th of what the speed is when having uTorrent in the foreground.

As soon as I bring uTorrent back to focus the download speed increases again. Very strange!

My hardware is top-notch with 500GB SSD disk, 16 GB RAM etc so it's not related to weak hardware for sure. I have no clue what this can be but my guess is that it's related to Windows 8 somehow, probably related to network task priority issue, and potentially a bug in uTorrent.

I have tried reinstalled uTorrent several times. I've tried v3.2.3 and now I'm on 3.3Beta but the problem remains.

Any clues?

Link to comment
Share on other sites

It's a 512GB Samsung 840 Pro Series SSD with a write speed of 'only' 520MB/s. It's a fast disk, even when writing to it. It's connected to a 6GB/s SATA controller and it's REALLY fast copying files.

My problem is that the download speed goes down to about 50KB/s (0,05MB/s) when uTorrent is in background.

You still think the disk is the problem?

Link to comment
Share on other sites

Can you repeat this behavior with a heavily seeded OpenOffice torrent to rule out coincidence please?

@ciaobaby: The fastest platter based disk I found is nowhere near low end SSD's in performance. Are you aware of an HDD that sustains >500MB/s with a payload greater then the cache size?

Link to comment
Share on other sites

Hi, Yes I can repeat it easily. It is not a cooincidence. For instance today my computer was idle while uTorrent was downloading in the background from well seeded torrents. When I changed focus to the uTorrent window in the speed history tab I saw about 200Kb/s as long as I could see in the 10 min history, but as soon as I changed focus to uTorrent it immediately jumped to about 2000Kb/s.

It's the same every time. Even when posting this message, I have uTorrent running, and if I switch to have uTorrent in focus it immediately increases download rate.

When uTorrent loses focus, the download speed does not drop immediately, but it slowly drops and it can take 10 min until the speed has fully dropped to a lower rate. But I can abort the dropping in speed by just changing focus to uTorrent once in a while.

I have tried everything I can imagine, including: scanned system for viruses (Malwarebytes) and none found, disabled firewall, increase thread priority to highest for uTorrent etc etc. but nothing helps. I have no other tasks working in the background that compete with resources.

I'm a computer engineer and have worked as a programmer for over 10 years so I am not a novice when it comes to computers, but this problem I cannot solve.

I still lean towards a bug in uTorrent related to net IO priority under win8, or related to uTorrent missunderstand the performance of my system and reduces rate due to some missunderstanding by uTorrent.

Is it possible to enable more verbose logging in uTorrent? It clearly is something that changes when goin in/out of focus of uTorrent, but I cannot see what it is.

Link to comment
Share on other sites

Ok, not much help in this forum, but I think I might have found the issue. Just in case someone else run into this, I'm sharing it here:

I had installed the latest version of ASUS AI Suit which is a suit of quite poorly developed programs by ASUS. One of the "tools" is Network iControl that is supposed to deliver "a smoother online experience".

Turns out that this crappy tool probably prioritize network traffic, giving higher priority to foreground tasks. There is also some notes about that.

Disabling this unuseful "software" seems to have helped.

Link to comment
Share on other sites

  • 3 months later...
  • 1 year later...

I just did something that I've never done before - registered on this forum just to say, THANK YOU, random internet stranger, for solving this mystery that bugged for the last 3 years! :)


It wasn't only uTorrent, ALL applications that were not in foreground were reduced to about 1/5 of the download speed. It seemed like I'm the only one in the world with this problem, for which I was unable to find a solution for, until now.

And, it was crappy Asus software all along... Well, who would've guessed... And, there is literally the ONLY thread about this matter that I managed to find, and I'm far, far away, from your regular internet or computer noob...


So, once again, THANK YOU, Joacim. And, sorry for necroposting, I just had to get this out of my system... :D

Link to comment
Share on other sites

  • 2 months later...


This topic is now archived and is closed to further replies.

  • Create New...