What OS you are using?
There may be too many reasons, checkout below if any one suits to the cause.

1.Check redo allocation in v$latch

when you get below a 99% hit ratio that you need to start looking out. The
following sql figures the current hit ratios for those latches:

column latch_name format a20
select name latch_name, gets, misses,
round(decode(gets-misses,0,1,gets-misses)/
decode(gets,0,1,gets),3) hit_ratio
from v$latch where name = 'redo allocation';

column latch_name format a20
select name latch_name, immediate_gets, immediate_misses,
round(decode(immediate_gets-immediate_misses,0,1,
immediate_gets-immediate_misses)/
decode(immediate_gets,0,1,immediate_gets),3) hit_ratio
from v$latch where name = 'redo copy';

If your Redo Allocation Latch hit ratio consistently falls below 99%, and if
you have a multi-CPU machine, you can lower the value for
log_small_entry_max_size in your init.ora file which says that any change
smaller than that will hang onto the Redo Allocation Latch until Oracle is
finished writing that change.

2.For shared_pool_size

select gethits,gets,gethitratio from v$librarycache
where namespace = 'SQL AREA';


If the gethitratio is less than 90%, you should consider increasing the
shared pool size


Best Regards
Jayashree



-----Original Message-----
From: Onicca Mnguni
[mailto:oracledba-ezmlmshield-x4144645.[Email address protected]
Sent: Thursday, January 31, 2008 1:17 PM
To: LazyDBA Discussion
Subject: Database slow

Hi Guys

My database is very slow, I need to know what could be causing it to be
slow.

Xoli


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