Seconds Behind Master increasing in slave

[Revathi Rangachari]

Hi

We have a master-slave setup.  The slave acts only as a replicate and does not cater to
any client requests.

Over the last 24 hours there has been more than 4 to 6 hours delay in the replication. 
The CPU, IO, memory usage all seem to be under control.  I changed the  SET GLOBAL
innodb_flush_log_at_trx_commit = 0 ;

The slave sql and io threads are running.
show processlist shows only one update statement on a table.

In spite of all this the slave still lags behind in replication by 5 hours. 
 
Any suggestion to improve the replication performance is highly appreciated.

Thanks
Revathi R