If I use the Primus or Speakeasy tests, I get around 5Mb.
If I use Speedtest.net, it goes down to around 1Mb or less... sometimes it even stalls out. I'm guessing Speedtest has a longer test, and it just can't finish.
Mind you, this is just between 9pm and 11pm - give or take 30 minutes each side. Rest of the time, I can pretty well max out.