I've made significant performance increases for the blockchain by creating
a custom database that outperforms the more conventional LevelDB. This is
still a work in progress and won't be in libbitcoin at least for some
time. You can read more about more research here:

https://wiki.unsystem.net/index.php/Libbitcoin/Blockchain

The results are drastic. Write speeds are reduced to 30%. Read speeds to
15%. We can even go further as this is an initial prototype. We haven't
yet applied all possible optimisations.