Inefficient vector resizing with reserve.

This operation, if performed to grow large vectors, may take a very long time to complete. A vector's capacity is increased with reserve in a manner that causes many unnecessary copies.
/src/mongo/db/catalog/index_consistency.cpp:285: INEFFICIENT_RESERVE 135025 A "std::vector" has its capacity adjusted with "reserve()" in a manner that is likely to have severe performance penalties.