You have noticed in both your SQL Server 2000 and 2005 instances that when a database grows in SQL Server, there is a delay in the database response.

Once the file is grown, zeros are written to the new space, causing a delay.When a database file grows, unless instant file initialization is turned on, the server must allocate disk space and then write 0s into all that space. This zero-ing out of the file creates the delay.