in any case the update of Constantinople failed the testing. perhaps the ethereum team is implementing everything with good results in January 2019.
The Ethereum constantinople upgrade failed on the testnet. That's the main reason, why Casper has been delayed for Ethereum until 2019. In the bright side, Ethereum will scale in the safest way possible compared with other alternatives which scale quickly without ensuring the quality of the implemented upgrades. As such, it's not quantity that matters (like number of TPS) but quality instead. If Ethereum could scale safely with it's Casper PoS and Sharding, then it would become a success.
By then, Ethereum will become one of the fastest cryptocurrencies in existence, just like in its early days. In the meantime, we could enjoy altcoins with near-instant speeds that make our life much easier. DAG cryptocurrencies seem to be the best bet towards allowing users to make micropayments at the least time possible without any additional costs. On the other hand, DPoS cryptocurrencies such as EOS and Tron are also fast with cheap costs. This means that cryptocurrencies are only getting better over time, which will result in massive adoption from people within the mainstream world.
Nonetheless, if you're looking into the fastest cryptocurrencies in existence, then DPoS and DAG cryptocurrencies are the ones that fulfil such purpose. It's been proven that PoW based cryptos like Bitcoin and Litecoin are extremely slow and resource intensive. Which is why, the future lies on PoS, DPoS, and DAG for greater scalibility and energy efficiency. Just my thoughts