I am guessing that you are in archive log mode. If so then you are saying that it is taking 1200ms to copy a 50mb file. Given that you are doing 600 megs of redo per hour it sounds like it is fine.

There is an article on metalink regarding increasing the size of your log buffer. Doc ID: 26904.996

From: Oracle, Tom Villane 29-Sep-00 18:52
Subject: Re : INCREASING THE PARAMETER : LOG_BUFFER

Hi,

If a user process has to wait for the LGWR to move redo entries from the buffer to the log files on disk, then it can affect performance. You can check to see if any users are waiting on buffer space by using the following. SELECT name, value FROM v$sysstat WHERE name = 'redo log space requests';

The value of "redo log space requests" should be near 0. If this value increments consistently, processes have had to wait for space in the buffer. This may be caused by the log buffer being too small, or it could be caused by the checkpointing or log switching.

The is no danger in making it larger. If an instance crashes, any uncommitted transactions are lost anyway. Making it larger uses more memory which could be used somewhere else.

Regards
Tom Villane
Metalink Analyst