> Technically, decentralized system will be
> always slower than centralized one.
There are application where speed matters. For example, to sort things out while all the lawyers are in a room.
Not inspiring confidence in the statement that it is faster than other systems. Compared to Bitcoin it is off by a constant factor, and constant factors aren't really what we're interested in here.
Storing an economy in a fully replicated global ledger has its limitations, there's no getting around that.
>bitcoin is significantly slower than other systems of its class
that class being decentralised proof-of-work, it is no slower than it is more secure than those class-members. (And among class members of equal 'speed' it is most secure)