Benchmarks

[ysimonson]

Initial results:

test memory::benches::iter          ... bench:       8,904 ns/iter (+/- 372)
test memory::benches::push          ... bench:          53 ns/iter (+/- 5)
test memory::benches::push_parallel ... bench:   6,643,523 ns/iter (+/- 490,757)
test sqlite::benches::iter          ... bench:     182,264 ns/iter (+/- 17,654)
test sqlite::benches::push          ... bench:   8,659,845 ns/iter (+/- 3,747,654)
test sqlite::benches::push_parallel ... FAILED

Sqlite is expected to run much slower since it's syncing to disk. push_parallel is currently failing because of heavy write contention causing DatabaseBusy errors. This should be addressable with wal2 mode + some other tweaks.