It is likely that the default settings will be suboptimal for your machine, even resulting in thrashing. If you post your basic specs I can make suggestions. One of the aspects we are working on is automatically tuning what is presently manual configuration for given platform.
Also note that if your CPU supports sha native (shani), which is about 5x faster individual hashing, it will distort realistic benchmarking, since shani is not yet integrated into the hashing library.