IO performance issues

Hi,
I want to begin by saying I'm relatively new with Informix and don't have advanced knowledge of how informix works.

I'm opening this thread because of some IO performance issues that I have now and need to be sure of what I must do.

This is my db profile counts:Profile
dskreads pagreads bufreads %cached dskwrits pagwrits bufwrits %cached
22906487 87848814 34363980245 99.93 332057743 398328761 1082072410 69.31

isamtot open start read write rewrite delete commit rollbk
48406998458 7423608018 9188986012 10875359326 1488886 347373130 682316 347179506 1

gp_read gp_write gp_rewrt gp_del gp_alloc gp_free gp_curs
1487097310 353965214 343076548 4397605 4723657 2 18018239

ovlock ovuserthread ovbuff usercpu syscpu numckpts flushes
0 0 0 457810.60 98673.63 3364 7580

bufwaits lokwaits lockreqs deadlks dltouts ckpwaits compress seqscans
541933 6627626 13923560081 0 0 29422 1170160 807177

ixda-RA idx-RA da-RA logrec-RA RA-pgsused lchwaits
70449 9643446 760355 1294 18020622 137838512

Onconfig:
NETTYPE soctcp,1,200,NET
LISTEN_TIMEOUT 60
MAX_INCOMPLETE_CONNECTIONS 1024
FASTPOLL 1
NUMFDSERVERS 4
NS_CACHE host=900,service=900,user=900,group=900

MULTIPROCESSOR 1
VPCLASS cpu,num=12,noage
VP_MEMORY_CACHE_KB 0
SINGLE_CPU_VP 0
CLEANERS 8
DIRECT_IO 1
LOCKS 20000
DEF_TABLE_LOCKMODE page
RESIDENT 0
SHMBASE 0x44000000L
SHMVIRTSIZE 10485760
SHMADD 262144
EXTSHMADD 51200
SHMTOTAL 62914560
SHMVIRT_ALLOCSEG 0,3
SHMNOACCESS
MAX_PDQPRIORITY 100
DS_MAX_QUERIES
DS_TOTAL_MEMORY
DS_MAX_SCANS 1048576
DS_NONPDQ_QUERY_MEM 256
DATASKIP
BUFFERPOOL default,buffers=10000,lrus=8,lru_min_dirty=50,lru_ max_dirty=60.5
BUFFERPOOL size=2K
BUFFERPOOL size=8K

The machine on which DB runs has 16 cpus and 64 GB of RAM.

These values are not configured by me.

Any ideeas ?

Thanks.