To prime caches means to fill the caches with data so that subsequent Directory Server behavior reflects normal operational performance, rather than ramp-up performance. Priming caches is useful for arriving at reproducible results when benchmarking, and for measuring and analyzing potential optimizations.
If possible, do not actively prime the caches. Let the caches be primed by normal or typical client interaction with Directory Server before you measure performance.
Tools for priming database cache can be found at http://www.slamd.com.