Do you have BTCloud?
I've found that it was due to the newly installed BT cloud program was hogging all the bandwidth, even when not downloading or uploading files!
speedtest when Bt Cloud running in background, with BT cloud paused & not actively uploading or downloading, speedtest shows 2mb/s download & 0.112mb/s upload!
When I quit Bt Cloud it jumps back up to 6.52mb/s & 0.345mb/s!
Re start Bt Cloud.... figures drop back down.... Grrrrr!
Quit Bt Cloud..... figures jump back up again!
I'm about to give up on Bt Cloud.
Note using a Macbook Pro OSX mountain lion.
I'm also trialing Google drive & Livedrive, these programs do not effect my broadband speeds!
ADSL line is testing ok.
I have had bt cloud installed since it was available and have never experienced your problem but I use w7. not seen any other posts like yours since cloud has been available but maybe this will get more people to post
I've had BT Cloud installed for quite a time now, with plenty of other issues (see various posts), but I haven't seen that one.
Johnoo posted earlier
If you are having problems with the Cloud, suggest you phone 0800 500 3114 where there is a person who will be able to assist you (I hope)
I've not tried it, but a couple of other posters had help from them, so try that.
I have just spent over 2 weeks with BT Broadband tech support trying to resolve my speed issues.
Finally, today, at my own suggestion, I disabled BT Cloud and all is back to normal. So Cloud has been the culprit from day one, and no one in BT seems to consider it as a potential threat to speed. What resolution?. I also have committed to 12 months to get the 50GB and it took forever to get it to work. And there is no copying of folders. But the bandwidth issue is the totally unacceptable defect. Yet to be resolved. Any one else experienced this, and found a resolution?