Closing ports except 22 and 443. This dramatically slows down the nmap scans:
-A INPUT -i eth0 -p tcp -m multiport --dports 22,443 -j ACCEPT -A INPUT -i eth0 -p tcp -j REJECT --reject-with icmp-port-unreachable
If I remove the REJECT rule, nmap is fast.
So how to make other ports look like closed ports without slowing down the nmap?