Sure, it is more efficient, actually it is not very hard to be more efficient, than the banking transaction system 
Still, I do not think banks will use Bitcoin, to make transactions faster.
Bitcoin and Cryptocurrencies provide an opportunity for everyone to directly transact peer to peer without intermediaries. This means that all Cryptocurrency users can see all transactions between users that occur involving the Cryptocurrency, without being able to tamper with the data because it is cryptographically locked and requires consensus agreement between the Miners. (Bitcoin can be regarded as digital gold, a network of developers who are expanding a network of Bitcoin transactions called Miners. They are the ones who are expanding the network of Bitcoin transaction blocks, auditing new transactions and printing new Bitcoin as gold miners increase the amount of gold by digging it up. Still, I do not think banks will use Bitcoin, to make transactions faster.