speed drop-down

Hi guys
I have problem with me router bored (RB2011UiAS-2HnD)
My speeds from ISP are 200 Mbps down and 80 Mbps Up
my configuration as :

either 1 = WAN 1 as ( PPPOE in )
either 2 = WAN 2 as (back up which disable )
either 3 = WAN 3 as(back up which disable )
either 4 = local
either 5 = bridge with local

if I disable the bridge my speed goes to normal (200 Mbps down) if I enable bridge my speed drop to max (100 Mbps )
so can you help me to solve that with 2 port as local one for me and one for my customers .