I also have Comcast and noticed that some of the Mirrors closer to where I live seem to be consistently faster. You might want to try one of testmy.net's mirror servers and test your connection there. The one I tested was http://www.testmy.net/o-mirrorBAF . My results are below:
:::.. Download Stats ..:::
Connection is:: 4121 Kbps about 4.1 Mbps (tested with 3151 kB)
Download Speed is:: 503 kB/s
Tested From:: http://www.bafserv.com
Test Time::
Bottom Line:: 74X faster than 56K 1MB download in 2.04 sec
Diagnosis: Awesome! 20% + : 20.04 % faster than the average for host (comcast.net)
Validation Link:: https://testmy.net/stats/id-LN620PGUS
