We are seeing some terrible performance degradation having just upgraded our MVC4 application from SQL 2008 to SQL 2012.
Queries run directly in management studio on the database server run somewhat slower than they did prior to the upgrade (up to twice as slow).
Queries run from the web server (a separate machine) run hugely slower, some more than four times slower. We pointed the finger at the network between the two machines, but our hosting company have suggested that the connection string should have changed for SQL 2012. I'm not aware that SQL 2012 connection strings are any different to SQL 2008 connection strings - am I right?
Our connection string has been unchanged for years and looks like this: Server=18.104.22.168;Database=MyDbName;User ID=MyDbUser;Password=MyDbPassword;
UPDATE: This eventually turned out to be a faulty physical port on the firewall!