I wonder if 5 SECONDS BLOCKTIME is something that makes us say that the Proof of Work (Ethash) algorithm is safe? This time is not enough to conduct a proper hash, broadcast the block, and start receiving new transactions to add to the new block.
It seems that the new blockchain is a hardfork of Ethereum, a faster version with cheaper fees, but I doubt it is secure.
I'm not ready to argue with you, but I will name a few coins with even less time
Nautilus(NTL) Karlsenhash algorithm, Nexellia(NXL) Karlsenhash algorithm, Karlsen(KLS) Karlsenhash algorithm - 1 second
Conflux(CFX) Octopus algorithm - 0.5 second
I haven't heard of any security issues with these blockchains and I've only written a few coins. In fact, there are many more of them.