I put build 15437 back on today and whilst browsing is quick and speed tests get the expected results, downloads aren't very good.
Downloading one of Virgin's game files is a good test and I usually get around 1,200 KB per second on my connection when it's working well, but with this build I get around a third of that speed, even when my connection is performing as well as it should.
http://gamefiles.virginmedia.com/blu...42/demo/win32/