I have written stored procedure which simply read each row one by one and update the some column in same table.

SP is running fine in SQL Server 2000 and completed within 5 minutes (around 5 million rows)

But same SP in SQL Server 2005, its taking around more than one hour (for same number of rows)

Note: Both server 2K and 2005 on same m/c.

Pl can you help me to know what are the possibilities and server setting have to change in 2005 to improve this performance.