I have this problem: i have installed mikrotik 2.9.27 and i have problem with port 80.My internet its 4MB/s and when i tested with mikrotik the bandwith it’s ok but the internet it’s very slowly!!!???WHY???i HAVE NO RULES ON FIREWALL ONLY CONFIGURATED NAT WITH masquerade and other simples rules. I tested the interface and its ok?i want to localize the problem on mikrotik because i dont know where is it!!! WHEN I PUT THE INTERNET in different router example Linksys the internet its ok. Sorry for my english very well english 
help me please
maybe you’re must change MSS, i.e. like this:
ip firewall mangle print
Flags: X - disabled, I - invalid, D - dynamic
0 ;;; Change MSS for outgoing traffic
chain=postrouting action=change-mss new-mss=1452 tcp-flags=syn protocol=tcp src-address-list=users out-interface=pppoe-out1 tcp-mss=1453-65535
First of all please upgrade to a newer version (legal hopefully..)..
do you use web proxy?