If you purchase performance memory, it allows the motherboard to use the performance values of the memory. The JEDEC memory standard is DDR3-1600 CL11, so when you have memory better than this, an additional profile is added to the memory known as Extreme Memory Profile (XMP). When the feature is enabled in your motherboard BIOS/EFI, the motherboard utilizes this profile from the embedded XMP Profile in the RAM. As a result, you don't have to manually input settings for the memory, everything is ready to go as long as your enable XMP. Enabling XMP allows the motherboard to automatically configure DRAM frequency, timings, and voltage according the the RAM's rated specifications.
If you purchased performance memory, why not use it to...