The bitcoin accounts package is a replacement of the build in account system in your bitcoind server. The main advantage over the bitcoind account system is that you can fully control your fee.

The package imports transactions from the bitcoind API. The import frequency is set in the config file. Because all the transactions are imported the account balance can be calculated without doing a bitcoin API call. This way it won't effect your performance load a lot.

There is an option to send transactions in a batch. So when you send a transaction, there won't be a direct API call.