For people who want to simply use it as a backend, a get_history command
allows to get the history for an address used to compute a balance or
show the history.

Also the way I imagine DW using SPV, is first trusting the server and
SPV validating in the background. This makes the wallet immediately
useful. Although there are privacy comprimises with fetching the history
for a fixed address, we can improve and iterate over time. The thing is
to have it working now.

http://www.reddit.com/r/Bitcoin/comments/2go7qm/devs_be_sure_to_test_your_bitcoin_apidata/

Those performance stats are simply impossible if we get a list of tx
hashes + fetch every single tx for them.