Throughput vs. Time to Finality

To measure blockchain performance we can use two metrics:

• Throughput: How many transaction are finalized per second measured in transactions per second (TPS)
• Time to Finality: How long does it take a transaction to go from being submitted to validators to being unchangeable.

These metrics are very different. Blockchain builders aspire to high throughput and very short time to finality.

Highway Analogy

Let's take an analogy of a highway. Each car represents a transaction and they all travel the same speed. When you click send in your wallet, you're like a car entering the highway. When the transaction is finalized and unchangeable, it's like the car reaching its destination.

Throughput could be likened to the number of lanes, determining how many cars can pass on the highway in a given amount of time. The more lanes you have, the more cars can pass through, thus increasing the throughput. In a blockchain network, increasing the block size (analogous to adding more lanes) can increase throughput.

Now, imagine you're driving to a specific destination (finality). The time it takes you to get from your starting point (initiation of the transaction) to your destination (confirmation of the transaction) is analogous to the "time to finality." As soon as a car reaches finality, it cannot return or abort the travel.

Our goal is to build highways with many lanes (high throughput) but that bring us to our destination as fast as possible (short time to finality).

Throughput and Finality of Popular Blockchain Networks

TPS → Transactions per Second

Returning to the highway analogy, these networks would look like this: