It's all so subjective. Many networks say that they have the fastest transactions, but because of the weak load, they can not prove it.
Exactly. Any cryptocurrency can be fast if it doesn't have high network load. Depending on the number of people using it for daily transactions, the speed can either increase or decrease, as well as, costs. Bitcoin could've been fast like old times if there wasn't any high network load at all. However, due to the increased adoption of Bitcoin as a cryptocurrency for the mainstream world, speeds have declined, and fees have risen, causing the need for the pioneer cryptocurrency to scale ASAP.
The same thing could happen with other cryptocurrencies since their speed and cost are determined with the current network load. While it's true that there are some consensus algorithms which are much efficient than others, they could become as slow as PoW if they gain high load. These are the facts, however many cryptocurrency projects are simply claiming to be the fastest, to bring a lot of hype from investors and ordinary people.
They would need to prove their speed by performing a series of tests, which anyone could audit. Speaking of this, Credits aims to be one of the fastest cryptocurrencies in existence. Compared with many overhyped cryptocurrencies, Credits has taken the opportunity to prove its claimed speed and security by performing an audit by a well-known company. This shows, that Credits is truly a cryptocurrency that could handle large TPS while delivering low fees and unparalleled security.
Other cryptocurrencies which are fast but haven't been put to the test are: Electroneum (Instant Transactions), and Lightning Bitcoin (LBTC). The last one uses a DPoS consensus algorithm, and it's quite fast compared with most cryptocurrencies out there on the market. However, its network load is low, which means that it's not as widely adopted and used as other popular cryptocurrencies we know and love today.
Nevertheless, time will tell us which cryptocurrency would stand the test of time, to deliver the fastest speeds and lowest costs, while retaining security and decentralization, which is most important. Just my opinion