Triple Duplicate Acks

["A System Admin" <asysad@gmail.com>]

Netfilter list,

We are seeing a fair amount of Triple Duplicate Acks between a
webserver that is using the following nat table prerouting redirect
and an application server....

*nat
:PREROUTING ACCEPT [0:0]
:POSTROUTING ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A PREROUTING -d <another hosts IP address>  -j REDIRECT
COMMIT

Here is our conntrack tcp parameters:

# for i in `ls /proc/sys/net/ipv4/netfilter/ip_conntrack_tcp*` ; do
echo "$i" && cat $i ; done
/proc/sys/net/ipv4/netfilter/ip_conntrack_tcp_be_liberal
0
/proc/sys/net/ipv4/netfilter/ip_conntrack_tcp_loose
3
/proc/sys/net/ipv4/netfilter/ip_conntrack_tcp_max_retrans
3
/proc/sys/net/ipv4/netfilter/ip_conntrack_tcp_timeout_close
10
/proc/sys/net/ipv4/netfilter/ip_conntrack_tcp_timeout_close_wait
60
/proc/sys/net/ipv4/netfilter/ip_conntrack_tcp_timeout_established
432000
/proc/sys/net/ipv4/netfilter/ip_conntrack_tcp_timeout_fin_wait
120
/proc/sys/net/ipv4/netfilter/ip_conntrack_tcp_timeout_last_ack
30
/proc/sys/net/ipv4/netfilter/ip_conntrack_tcp_timeout_max_retrans
300
/proc/sys/net/ipv4/netfilter/ip_conntrack_tcp_timeout_syn_recv
60
/proc/sys/net/ipv4/netfilter/ip_conntrack_tcp_timeout_syn_sent
120
/proc/sys/net/ipv4/netfilter/ip_conntrack_tcp_timeout_time_wait
120
#

Is there anything that can be done from the conntrack perspective to
lessen/eliminate the Triple Duplicate Acks?