Problem with Speed-Limit on Bridged Port / RB3011UiAS

Hi!

I want to limit a customers Ethernet-Port to 200M/50M (down/up).
The RouterBoard does strange things, when bridge will enable “Use IP firewalling”.

# dec/01/2015 15:44:05 by RouterOS 6.33.2
# software id = N68D-40SQ
#
/interface bridge
add name=br1-internet protocol-mode=none
/interface ethernet
set [ find default-name=ether1 ] name=eth1-rsm-connect-lwl
set [ find default-name=ether2 ] name=eth2-customer-firewall
set [ find default-name=ether3 ] name=eth3
set [ find default-name=ether4 ] name=eth4
set [ find default-name=ether5 ] name=eth5
set [ find default-name=ether6 ] name=eth6-management
set [ find default-name=ether7 ] name=eth7
set [ find default-name=ether8 ] name=eth8
set [ find default-name=ether9 ] name=eth9
set [ find default-name=ether10 ] name=eth10-backup-richtfunk
/interface bridge port
add bridge=br1-internet interface=eth1-rsm-connect-lwl
add bridge=br1-internet interface=eth2-customer-firewall
/interface bridge settings
set use-ip-firewall=yes
/ip address
add address=192.168.88.1/24 interface=eth6-management network=192.
/system clock
set time-zone-name=Europe/Berlin
/system routerboard settings
set protected-routerboot=disabled

When the ports assigned to the bridge, everything will go fine, but after setting

/interface bridge settings
set use-ip-firewall=yes

i am only able to get around 2 MBits.

While downloading a 4 GByte file i can see the limits in time.
=yes —> 2 MBit
= no → full speed

What is wrong with that hardware?
Would you tell me that RB3011 is not capable for this scenario?