This hotfix also applies to Microsoft SQL Server 2014 Analysis Services (SSAS 2014).
Symptoms
In Microsoft SQL Server 2012 Analysis Services (SSAS 2012) or SQL Server 2014 Analysis Services (SSAS 2014), the performance of an Multidimensional Expression (MDX) query may be much slower than the performance of the same query in early builds of SQL Server 2008 R2 Analysis Services (SSAS 2008 R2). This issue occurs if the query uses calculated members and Sub Select statement. Generally this kind of query is created by Excel.
Resolution
The issue was first fixed in the following cumulative update of SQL Server.
Cumulative Update 1 for SQL Server 2012 SP2 /en-us/help/2976982
Cumulative Update 2 for SQL Server 2014 /en-us/help/2967546
Cumulative Update 10 for SQL Server 2012 SP1 /en-us/help/2954099
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:
Status
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.