Cisco E2000 Performance Degrades over time on Comcast

I've got a Cisco E2000 (from last summer) - the performance seems to degrade over the course of days or weeks.  

If I reboot the router, speed (from speedtest.net) goes from 3Mbps to 7 or 8Mbps.

I'm not sure if this is because of Comcast powerboost, but it seems more likely that it's some bug in the firmware.

I've just upgraded the firmware to v 1.0.04, maybe that will help.