I receive a 16000 items values over zabbix trapper every 5 minutes on zabbix proxy, and observe a huge lag betwen zabbix server and zabbix proxy, more than 2 hours ..
Both machines that is zabbix server and zabbix proxy have a more than 90% of CPU idle, and a lots of ram free, and there is no network lag between them (ping latency aprox 0.107 ms)

Proxy config:

ProxyMode=0
Server=192.168.0.40
ServerPort=10051
Hostname=proxy_41
ListenPort=10051
SourceIP=192.168.0.41
LogFile=/var/log/zabbix/zabbix_proxy.log
LogFileSize=0
DebugLevel=3
PidFile=/var/run/zabbix/zabbix_proxy.pid
DBHost=
DBName=zabbix
DBUser=zabbix
DBPassword=xxxxxxxxxxxxxx
DBSocket=/var/lib/mysql/mysql.sock
ProxyLocalBuffer=0
ProxyOfflineBuffer=24
ConfigFrequency=60
DataSenderFrequency=1
StartPollers=256
StartTrappers=384
StartPingers=200
StartDiscoverers=10
StartHTTPPollers=0
SNMPTrapperFile=/opt/snmpprobe/log/share/zabbix.log
StartSNMPTrapper=1
HousekeepingFrequency=1
CacheSize=128M
StartDBSyncers=40
HistoryTextCacheSize=64M
ExternalScripts=/usr/lib/zabbix/externalscripts
LogSlowQueries=1000

Server config:
LogFile=/var/log/zabbix/zabbix_server.log
LogFileSize=0
PidFile=/var/run/zabbix/zabbix_server.pid
DBHost=
DBName=zabbix
DBUser=zabbix
DBPassword=xxxxxxxx
SNMPTrapperFile=/var/log/snmptt/snmptt.log
CacheSize=32M
HistoryCacheSize=64M
TrendCacheSize=32M
HistoryTextCacheSize=64M
AlertScriptsPath=/usr/lib/zabbix/alertscripts
ExternalScripts=/usr/lib/zabbix/externalscripts

Stats from zabbix server and zabbix proxy are fine, utylization is minimal.

Number of records on zabbix proxy db continually grows, it’s seams that the problem is on zabbix proxy, I caught by tcpdump packet transmitted between zabbix proxy and zabbix server and it have a 2 hours delayed clock field.

I use:

Name : zabbix-proxy-pgsql
Arch : x86_64
Version : 2.4.4
Release : 1.el6
Size : 1.3 M
Repo : installed
From repo : zabbix

Name : zabbix-server-pgsql
Arch : x86_64
Version : 2.4.4
Release : 1.el6
Size : 4.3 M
Repo : installed
From repo : zabbix

Installed Packages
Name : postgresql94
Arch : x86_64
Version : 9.4.1
Release : 1PGDG.rhel6
Size : 5.4 M
Repo : installed
From repo : pgdg94

I try to recreate zabbix proxy db but it does nothing.