Vitalik Buterin has suggested that the Ethereum blockchain is unlikely to get much faster despite planned upgrades.
Buterin’s comments came yesterday in response to a Reddit user’s question about why the switch from proof-of-work to proof-of-stake would not reduce block confirmation times.
As with most blockchain-related problems, optimizing one variable (e.g., speed) likely comes at the expense of another (e.g., network security). The tradeoff between speed (block time) and decentralization/security exists regardless of whether a network is proof-of-work or proof-of-stake, albeit for different reasons.
With proof-of-work, the “core issue,” according to Buterin, is the built-in randomness of block time. Ethereum does have an average block time of 13 seconds, but that does not mean a block is actually written every 13 seconds. There is some chance that a new block will be validated just one second after the last one is confirmed, Buterin explained. In that case, the prospector with a better network connection is more likely to be the first to propagate the next block. Shortening block times makes this problem much worse.
With proof-of-stake, there is another factor at play. The version of proof-of-stake that Ethereum will use, Buterin writes, requires blocks to get about 9,100 signatures per slot in order to be recorded, allowing for a “very high level of confirmation after just one slot.” Because the time required for this process is logarithmic rather than linear, cutting the slot time in half (requiring only about 4,550 signatures) “would not work because each now-shorter slot would still take almost as long.” Shortening block times would result in many signatures being excluded from the blockchain and “highly centralized players” would be in an increasingly favorable position to make disproportionate profits.
Buterin, therefore, concludes that future upgrades will not represent a significant reduction in “time per slot” and that applications requiring fast confirmations will have to rely on channels or rollups.
Leading developers from other Layer 1 chains also weighed in on the discussion on Twitter. The founder of Ava Labs, which developed Avalanche, Emi̇n Guen Si̇rer, tweeted at Buterin and appeared to criticize him for his choice of chain parameters, which Sirer said make consensus a bottleneck. Buterin responded that Sirer should “stop being dishonest” and clarified that his earlier claims that consensus was not the bottleneck referred to bandwidth, not latency.
The discussion continued and Anatoly Yakovenko, the co-founder of Solana Labs (developer of Solana), also came forward with his own questions about signature requirements as a function of slot times. The co-founder of Dogecoin also joined the dialog, asking Sirer why he named his “cryptocurrency after something that falls down.”