Have you checked your Juniper firewall QoS settings?
After I migrated to Comcast from dual 3 mbps DSL circuits going through a Cisco dual WAN router, I also initially saw really crappy performance.
I checked and double checked my router/firewall settings, and everything looked as is should. I had previously setup QoS to optimize my slower DSL connections for VoiP, and after I changed the WAN settings from dual WAN PPPoE to a single WAN with DMZ for the new Comcast connection, those old QoS settings had seemingly been deleted. However, even though I could no longer see those old QoS config settings, they were still being used by the router. It took a factory default reset of the router, and manual reentry of all of my firewall rules to get proper performance with the new Comcast connection.--
We can never have enough of nature.
We need to witness our own limits transgressed, and some life pasturing freely where we never wander.