Users who use ZkSync Era or Polygon ZkEVM have big problems with transaction fees that are too high, especially compared to other Ethereum scaling solutions like Optimism or Arbitrum. So what is the reason? Let's find out in the article below!
Update Layer 2 and Ethereum Context
Currently, Ethereum is still the leading Layer 1 blockchain and the destination of countless large and small projects in many different sectors (Lido Finance, MakerDAO, Blur...). With the attraction of huge money flows to the chain, the number of daily users on Ethereum is still superior compared to other chains.
Ethereum's superiority over other projects including Arbitrum , Optimism , ZkSync Era and Polygon ZkEVM is understandable due to its large, long-standing ecosystem and high security.
However, Ethereum's biggest problem right now is its low TPS and high Gas Price . once the number of transactions spikes, congestion as well as Gas spikes will often occur. The closest you can see is when Ethereum Gas Price hit a record high ahead of $PEPE listing Spot on Binance . Besides, because of high security, scalability is also clearly limited on Ethereum.
That's when Ethereum's Layer 2 scaling solutions started to appear with increased transaction processing speeds, reduced latency, and high scalability. Compared to Ethereum's average Gas Price per transaction per day of around $4, the other four projects in the table show much better fees.
Layer 2 Optimism and Arbitrum have both proven effective through their user base, the community is now moving towards more “futuristic” blockchain technologies with Zero-knowledge proofs. This is an interplay of scalability, fast transaction processing with low fees, saving users billions of dollars instead of using Ethereum itself, and an impressively secure platform.
Overview of Optimistic Rollups and Zk-Rollups
The “Rollup” solution means “to roll up”. This is a method in the Blockchain to process transactions that are Off-Chain (in this case, Ethereum). Instead of executing transactions directly on the main chain, they are processed on an independent Rollup layer.
After the transaction has been processed, the information is wrapped into a single block and sent to the Layer 1 chain for validation. Performing the entire computation Off-Chain on Layer 2 eases the load on the main chain.
For example: When completing a normal book, the reader will need to go through the process of reading all the pages, but with Rollup , all information and knowledge will be reduced to a single page, thereby reducing time. consumption time and energy consumption.
Read more: What is Rollup?
Optimistic Rollups
The project aims to assume that all transactions posted on the chain are considered valid, and when an invalid transaction is detected, the bug detector can submit a fraud proof (Fraud Proof). ) and the smart contract that handles the Rollup process will verify and compare it with the data available on Layer 1. Specifically, this mechanism can be understood by assuming that I am presumed innocent until I have proof that I am guilty.
Zk-Rollups
Contrary to Optimistic Rollup, Zk Rollup approaches the problem by ensuring the validity of transactions. Zk Rollup uses Validity Proof, which is SNARK, to prove the validity of transactions without recomputing those transactions.
Why is the transaction fee on Zk-EVM higher than Optimistic Rollups?
Upgrade of Optimistic Rollup
The first lies in the complete Optimism Bedrock update , which improves the network's functionality by cutting deposit confirmation times and reducing Gas Price for transactions by 40%. As a result, the average daily Gas Price of Optimism only fluctuates at about $0.09.
While Optimistic Rollups can be compatible with EVM, Zk-Rollups cannot. And before the requirement to combine 2 expansion factors, cheap fees and still maintain the security of the original L1 chain, ZkEVM is gradually emerging.
In terms of technology, one thing that can be clearly seen in the transaction fee difference between these 2 L2s is the complex technology applied in the system.
Read more: What is ZK-EVM? Can projects using this technology explode?
Fixed cost of Zk Rollups
In Ethereum, more users will increase Gas Price because demand is proportional to price increase. But with Zk-based Layer 2 solutions it is different.
With Zk-Rollups there are 2 types of fees:
- Fixed cost to create and send proof.
- The background fee due to having a sidechain with Ethereum (EVM) leads to a link to Ethereum's fees. (Variable Gas Price per transaction)
When there are fewer transactions , the fixed cost (to create the proof) distributed to fewer users causes Gas Price to increase. Conversely, as transaction volume increases, fixed costs are allocated and fees decrease. It can be understood that when sharing taxi fare, the amount each person has to pay will decrease when more people move together.
According to the above data, currently the daily transaction volume on the network of ZkSync with Polygon ZkEVM is not high enough to reduce the transaction fee. The number of 2 projects so far has only stopped at less than 100,000 transactions, to achieve the reduction, the number of transactions must reach 500,000 per day.
For Optimistic Rollup , there are the following differences:
- Since there is no need to generate zk-SNARKs proof, the cost will be lower.
- Still need to push data On-Chain to use the same Fraud Proof (Read more in What is Rollup? ) -> more fees than Zk-rollup.
In general, both Optimistic Rollup or Zk-Rollup technologies have advantages and disadvantages at certain stages. However, zkEVM only announced the mainnet at the end of March 2023, while Layer 2 Optimistic Rollup like Optimism or Arbitrum have been mainnet for a long time and have many transactions on the network, since then have benefited from the network effect. (Network Effect) . This is the main reason why the Gas Price of Optimism or Arbitrum is very low compared to zkSync Era or Polygon zkEVM.
Identify
The battle between Layer 2 is gradually heating up again...
Currently, Optimistic Rollups are still dominant and will probably still lead the solution to replace Ethereum within 2-3 years. Arbitrum and Optimism are typical names for this technology.
Meanwhile, Zk technology combined with EVM still needs more time to perfect and prove the theoretical effects through data from users. Vitalik Buterin himself, the founder of Ethereum, has repeatedly expressed his admiration for Zk-EVM but also affirmed that they still need time to improve transaction fees.
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