Poor FreeBSD Performance under cacti/snmp usage when using remote shell

[S H A N]

hi folks,

I am observing that for a machine with the following specs:-

Copyright (c) 1992-2005 The FreeBSD Project.
Copyright (c) 1979, 1980, 1983, 1986, 1988, 1989, 1991, 1992, 1993, 1994
        The Regents of the University of California. All rights reserved.
FreeBSD 6.0-STABLE #3: Thu Jan 26 20:38:29 SGT 2006
    root at ix-nw.ix.singtel.com:/usr/obj/usr/src/sys/IX-NW
Timecounter "i8254" frequency 1193182 Hz quality 0
CPU: Intel(R) Xeon(TM) CPU 2.80GHz (2791.01-MHz 686-class CPU)
  Origin = "GenuineIntel"  Id = 0xf29  Stepping = 9

Features=0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE>
  Features2=0x4400<CNTX-ID,<b14>>
  Hyperthreading: 2 logical CPUs
real memory  = 4160552960 (3967 MB)
avail memory = 4074123264 (3885 MB)
-- snip --
amr0: <LSILogic MegaRAID 1.51> mem 0xfebf0000-0xfebfffff irq 72 at device
8.0 on pci8
amr0: <LSILogic PERC 4/Di> Firmware 2.37, BIOS 1.05, 128MB RAM
-- snip --
amrd0: <LSILogic MegaRAID logical drive> on amr0
amrd0: 104034MB (213061632 sectors) RAID 5 (optimal)
ses0 at amr0 bus 0 target 6 lun 0
ses0: <PE/PV 1x6 SCSI BP 1.1> Fixed Processor SCSI-2 device
ses0: SAF-TE Compliant Device

configured with:-

em0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
        options=b<RXCSUM,TXCSUM,VLAN_MTU>
 -- snip --
        ether 00:0b:db:94:f8:65
        media: Ethernet autoselect (100baseTX <full-duplex>)
        status: active

and running cacti/snmp applications (to poll 83 network devices/1831
interfaces in less then 9secs for every 300sec) is hitting these kind of
gstats

dT: 0.501  flag_I 500000us  sizeof 240  i -1
 L(q)  ops/s    r/s   kBps   ms/r    w/s   kBps   ms/w    d/s   kBps
ms/d   %busy Name
   46    315      0      0    0.0    315   5491  138.3      0      0    0.0
99.9| amrd0
   46    315      0      0    0.0    315   5491  139.8      0      0    0.0
99.9| amrd0s1
   46    315      0      0    0.0    315   5491  139.9      0      0    0.0
99.9| amrd0s1f

for consistently few minutes... while the memory condition is reported to
be:-

Active:    288006144 Bytes
Inactive: 3293306880 Bytes
Wired:     218345472 Bytes
Reserved:    5644288 Bytes
Cache:     192761856 Bytes
Kernel:       139264 Bytes
Interrupt:      8192 Bytes
Buffer:    117211136 Bytes

Total:    4078235648 Bytes
Free:       85340160 Bytes

my question would be is that an acceptible behaviour? i.e. should i look for
upgrade or is there a tuning which can still make something out of it?
because when i access this m/c for usual tasks of editing files and copy
stuff it sometimes hangs for few minutes..

it is a source compiled box with the following make.conf

--- make.conf ---
# apache
WITH_APACHE_PERF_TUNING=yes
WITH_THREADS_MODULES=yes
# libiconv
WITHOUT_EXTRA_ENCODINGS=yes
# php
WITH_GD=yes
# gd
WITH_XPM=yes
WITH_LZW=yes

# mysql
WITH_CHARSET=latin1
WITH_XCHARSET=latin1
WITH_PROC_SCOPE_PTH=yes
BUILD_OPTIMIZED=yes
BUILD_STATIC=yes

#mtr
WITHOUT_X11=yes
# snmp

NET_SNMP_SYS_CONTACT="shanali at singtel.com"
NET_SNMP_SYS_LOCATION="Telepark"
DEFAULT_SNMP_VERSION=3
NET_SNMP_MIB_MODULES="host smux ucd-snmp/diskio"
NET_SNMP_LOGFILE=/var/log/snmpd.log
NET_SNMP_PERSISTENTDIR=/var/net-snmp

#make
MAKEOPTS=-j4

#noprofile
NO_PROFILE=     true
# added by use.perl 2006-01-26 21:28:26
PERL_VER=5.8.7
PERL_VERSION=5.8.7
--- make.conf ---

while cacti is doing pretty fine...

06/22/2006 06:10:09 PM - SYSTEM STATS: Time:7.9338 Method:cactid Processes:1
Threads:30 Hosts:83 HostsPerProcess:83 DataSources:3218 RRDsProcessed:1831
06/22/2006 06:15:12 PM - SYSTEM STATS: Time:9.7663 Method:cactid Processes:1
Threads:30 Hosts:83 HostsPerProcess:83 DataSources:3218 RRDsProcessed:1819
06/22/2006 06:20:09 PM - SYSTEM STATS: Time:7.6809 Method:cactid Processes:1
Threads:30 Hosts:83 HostsPerProcess:83 DataSources:3218 RRDsProcessed:1831
06/22/2006 06:25:10 PM - SYSTEM STATS: Time:8.2421 Method:cactid Processes:1
Threads:30 Hosts:83 HostsPerProcess:83 DataSources:3218 RRDsProcessed:1831
06/22/2006 06:30:10 PM - SYSTEM STATS: Time:8.6010 Method:cactid Processes:1
Threads:30 Hosts:83 HostsPerProcess:83 DataSources:3218 RRDsProcessed:1831

Any assistance on where to look for an appropriate tuning would be much
appreciated.

-- 
Best Regards.