When I have send a request to an application running on a machine which following firewall rules are applied, it waits so long. When I have deactivated the iptables rule, it responses immediately. What makes communication so slow?

-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
-A INPUT -p tcp -m tcp --dport 22 -j ACCEPT
-A INPUT -p esp -j ACCEPT
-A INPUT -i ppp+ -j ACCEPT
-A INPUT -p udp -m udp --dport 500 -j ACCEPT
-A INPUT -p udp -m udp --dport 4500 -j ACCEPT
-A INPUT -p udp -m udp --dport 1701 -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -i lo -m state --state NEW,RELATED,ESTABLISHED -j ACCEPT
-A INPUT -m limit --limit 5/min -j LOG --log-prefix "iptables denied: " --log-level 7
-A FORWARD -i ppp+ -m state --state NEW,RELATED,ESTABLISHED -j ACCEPT