On my Dell vostro 3550 note book with Windows7 64 bit and 8GB memory everything locks up or goes really slow after restoring the sql 2014 db backup to active sql express 2014 instance.
Solution : In SQL,applications that are migrated from earlier versions of SQL Server should be carefully tested to confirm that good performance is maintained or improved. If performance degrades like our case, you can set the database compatibility level to 110 (Default compatibility-level setting is 120 for sql 2014) or earlier to use the older query optimizer methodology. So we can achieve the same by running the following query for the specified restored database.
ALTER DATABASE database_name
SET COMPATIBILITY_LEVEL = 110;