Pass configuration along when opening sessions.
Start with a more rational default configuration.  (Before you ask... the
answer is 'no').  So far there has been no effort to validate that these
settings are in fact the best for Riak/KV or CS data access patterns.  These
particular settings are, at best, an educated guess based on past experience,
the docs and reading about the benchmark the WiredTiger team published here:

https://github.com/wiredtiger/wiredtiger/wiki/YCSB-Mapkeeper-benchmark
Change the config to use a lsm tree rather than btree for tables.
Stop using direct_io as it forces operations to sync more often, slowing
things down, at the expense of double-buffering (this will use more RAM).
Build from source pulled from a specific branch on GitHub for "basho"
related work and integration of WiredTiger rather than the latest
.tar.bz2 file they distribute.