I think that EOS and POA are now the fastest, but no one uses EOS, since it is super expensive, and nobody knows about POA in the world yet.
As far as I know, EOS is extremely cheap when compared with Ethereum. There are no fees per transaction, and speeds are blazing fast. While there's a cost involved when creating an EOS account, it's affordable and anyone can join the EOS network if they have the minimum required EOS for RAM. On the other hand, POA is not exactly a cryptocurrency but a sidechain which relies on the security of the Ethereum blockchain. Like Loom Network's sidechains concept, POA achieves true scalability on the Ethereum blockchain by allowing developers to deploy their dApps on the POA Network.
This approach allows smart contracts and token transactions to be faster and cheaper than the Ethereum blockchain itself. Which in effect, makes POA one of the fastest sidechains in existence, as well as, the Loom Network. While the POA Network is still unknown to many, it provides many benefits that solve the scalability dilemma. Loom Network's Plasma Chains work the same way, but for these sidechains to really take off, they would need better marketing/promotion.
Other cryptocurrencies which aim to become the fastest ones in existence would be IOST, Constellation, and Zilliqa. The first one named IOST will use sharding and a unique consensus algorithm named PoB (Proof of Believability), to provide unparalleled transaction speeds and low costs. The other one named Constellation will use a DAG just like IOTA and NANO for limitless scalability. And finally, there's Zilliqa which aims to become a smart contract platform like Ethereum with sharding and a formal verification language known as Scilla.
Therefore, new cryptocurrencies would emerge over time which are faster and cheaper than ever. It's the future of borderless payments and could greatly threaten Bitcoin's place as the first largest cryptocurrency by market cap within the future. Just my opinion