OnConfig parameters tuning

Hi guys, I'm trying to speed up an IDS 9.30 on a Sun 7.5 system w/ 2Gb ram and 4 processors that seems very slow on a large sequential write (I suppose that the problem resides in the dbspaces on filesystem...). Any suggestion? My onconfig it's set as follow: # System Configuration SERVERNUM 0 # Unique id corresponding to a OnLineinstance DBSERVERNAME sbn # Name of default database server DBSERVERALIASES sbn_tcp # List of alternate dbservernames DEADLOCK_TIMEOUT 60 # Max time to wait of lock in distributed env. RESIDENT 0 # Forced residency flag (Yes = 1, No = 0) MULTIPROCESSOR 1 # 0 for single-processor, 1 formulti-processor NUMCPUVPS 4 # Number of user (cpu) vps SINGLE_CPU_VP 0 # If non-zero, limit number of cpu vps toone NOAGE 0 # Process aging AFF_SPROC 0 # Affinity start processor AFF_NPROCS 0 # Affinity number of processors # Shared Memory Parameters LOCKS 120000 # Maximum number of locks BUFFERS 262144 # Maximum number of shared buffers NUMAIOVPS # Number of IO vps PHYSBUFF 64 # Physical log buffer size (Kbytes) LOGBUFF 64 # Logical log buffer size (Kbytes) CLEANERS 1 # Number of buffer cleaner processes SHMBASE 0x0A000000L # Shared memory base address SHMVIRTSIZE 8000 # initial virtual shared memory segment size SHMADD 32768 # Size of new shared memory segments (Kbytes) SHMTOTAL 0 # Total shared memory (Kbytes). 0=>unlimited CKPTINTVL 300 # Check point interval (in sec) LRUS 8 # Number of LRU queues LRU_MAX_DIRTY 60 # LRU percent dirty begin cleaning limit LRU_MIN_DIRTY 50 # LRU percent dirty end cleaning limit TXTIMEOUT 0x12c # Transaction timeout (in sec) STACKSIZE 64 # Stack size (Kbytes) --