That pretty much shows it can't be a defect in WIn7. Something I think would have been found by now in corporates given how many are moving fast from XP to 7.
My thoughts exactly.
Having said that, I was getting very low results right up to the point I tweaked.
Almost 30Mbps difference between a single thread speed test (and the multi thread test from the same provider) to a few Mbps difference immediately after tweaking (and with repeatability - essential for accurate diagnosis).
I was sticking to my guns (about BT throttling) but kept getting shot down in flames ("not possible", "BT don't throttle", "no congestion", "BT can't do local throttling", "BT can't throttle individual threads", "mine's OK so it must be you", blah, blah, the usual "helpful" responses).
Oddly enough, all the way through I was getting maximum speed from Usenet and other multi-thread downloads (which proved congestion wasn't an issue).
The poor peak time speed, and it only affecting single thread downloads, was reinforcing my view it was BT throttling individual threads.
Then, suddenly, all is OK following my tweaking the other day (now single thread downloads are almost as fast as multi thread - which has never happened before, during peak time, with my 80/20 product).
vDSL2 FTTC Infinity with BT
DL Sync 80Mbps
UL Sync 20Mbps