Symptoms
Assume that you use Microsoft SQL Server 2012 or SQL Server 2014. Time taken by SQL Server to open the database post recovery would gradually increase when the number of files in the database or databases increases.
Cause
The issue occurs because there is inefficient code in the SQL Server startup phase when the number of databases or database or both files is large.
Resolution
The issue was first fixed in the following cumulative update of SQL Server.
Cumulative Update 1 for SQL Server 2014 /en-us/help/2931693
Cumulative Update 9 for SQL Server 2012 SP1 /en-us/help/2931078
Each new cumulative update for SQL Server contains all the hotfixes and all the security fixes that were included with the previous cumulative update. Check out the latest cumulative updates for SQL Server:
Workaround
To work around the issue, reduce the number of data files in the database.
Status
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.