ENDIAN Firewall - Internet spped issue

Hi everyone.
I have an issue with internet access to internet, via ENDIAN 2.5.1 (virtualized). My ISP has 20Mbits bandwith; the LAN has static IP addresses with 20 hosts.
When i assign automatic IP to any host, the DHCP from the ISP allows me internet access to full maximum speed.
However, with endian DHCP, or static IP from any host, the internet access is slow...
I have taken a look to real time logs, but i see no DROPs or DENYs that may be causing this slowness...

Can anyone give me some tips about where to start looking in EFW configuration? any key parameters to have in count in order to solve it?

Thanks in advance for your help.

Emilio Leyes