Performance is slow when you open and read event files (.xel) by using XEvent Linq reader in Microsoft SQL Server 2012 or SQL Server 2014.
Service pack informationThis problem requires a client fix, not a SQL Server engine fix.
Note This change doesn't affect sys.fn_xe_file_target_read_file.
To resolve this problem, get Service Pack 3 (SP3) for SQL Server 2012.
bugs that are fixed in SQL Server 2012 Service Pack 3 .
Cumulative Update informationThe issue was first fixed in the following cumulative update of SQL Server.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.