The below graphs show two minutes of reads and writes against a PostgreSQL database running inside VMWare on a modern 2-core laptop, with #ops per second and response time plotted in each case. The initial high response time for writes is caused by the connection pool filling.
Half-way through, where the lines spike, the database is split (repartitioned) into two partitions - one being the original, the second newly created that second. Both of the new databases are on the same host, but this is a trivial detail.
More soon :-)