network Printer very slow

Hi
I have Brother MFC-J6910DW when avast internet security is installed it prints very slow.
It is a network printer connected via Ethernet. It also did the same with wireless connection. With usb connection it works fine.
If I turn off avast still slow, If I uninstall avast all works fine.
It also worked fine with the free avast, problem started after upgrade

any ideas??

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