Applying security to a cube comes at a cost to query performance. However, since we don't usually have a choice about whether to apply security or not, we then need to understand which security features have the least impact on performance when choosing which ones to use. In this final section we'll give some details on the relative impact on query performance of each type of security.
Cell security has by far the biggest negative impact on query performance, and for this reason alone it should only be used when there is no other option. Also remember that there are two different types of cell security, Read and Read Contingent; Read Contingent cell security has more impact on query performance than Read. The reason why cell security is so bad is because it prevents Analysis Services from using many important query optimization techniques (for example, in many cases it appears to completely prevent the use of the Formula Engine cache, so the results...