Binary sort order is the fastest sort order option. The overall performance difference between sort orders varies significantly depending on the types of operations and the type of data used. Sorting operations that depend on string comparisons in character fields (for example, GROUP BY and LIKE statements) take more time to process than other sorting operations and have the greatest effect on sorting speed.
With certain queries, if there is a nonunique clustered index on a character value, sort order options that define uppercase preference require the optimizer to perform a sort. Using a sort order with no uppercase preference, such as dictionary order, case-insensitive (no uppercase preference), improves performance because no sorting is necessary. Choosing dictionary order, case-insensitive (no uppercase preference), causes an uppercase A and a lowercase a to be treated equally in an ORDER BY statement.