Flashblocks: Towards ultra-fast layer 2 EVMs?
March 7, 2025
The evolution of Ethereum Rollups is progressing rapidly with the launch of Rollup-Boost by Flashbots. Already adopted by Unichain and recently implemented by Base, this technology—also known as "Flashblocks"—promises to optimize Layer 2 performance by drastically reducing confirmation times while strengthening MEV management.
Background on Flashbots
Flashbots is a major organization in the industry, specializing in research and development of block production solutions across various blockchains, starting with Ethereum. Their primary goal is to mitigate the negative impacts of Maximum Extractable Value (MEV) while bringing transparency and fairness to the process.
Note: MEV, or Maximum Extractable Value, refers to the maximum value that validators can extract from a block by ordering transactions in a specific way. MEV can be seen as positive when it enables faster liquidations or arbitrages, or negative when it involves practices like front-running or sandwich attacks, which directly extract value from users.
Flashbots’ main product is MEV-Boost, an open-source program that allows validators to benefit from the highest MEV yields while protecting the network from harmful MEV.
MEV-Boost has long been the most widely used program by Ethereum validators, at one point securing over 70% of the network. However, due to decentralization concerns, competing solutions have emerged, fostering greater competition.
What is Rollup-Boost by Flashbots?
Introduction to Rollup-Boost
On October 10, 2024, Flashbots announced the launch of a new product: Rollup-Boost, a platform designed to enhance the performance, programmability, and decentralization of Ethereum Rollups.
More specifically, Rollup-Boost is a block-building platform for Rollups that enables fast confirmations, provides guarantees to users, and internalizes MEV. It is based on Trusted Execution Environment (TEE) technology.
Note: A TEE, or Trusted Execution Environment, refers to a secure environment within a physical machine. It allows the storage of sensitive data and execution of complex computations while ensuring integrity and protection against attacks, including from the machine's owner.
Rollup-Boost operates as a set of modular Rollup extensions that can be implemented to improve performance, programmability, or decentralization. Currently, two initial extensions have been introduced:
- Flashblocks, which offer ultra-fast confirmation times of 250ms and faster gas throughput.
- Verifiable priority ordering within Flashblocks, providing better guarantees for users and allowing applications to internalize MEV.
Benefits for Rollups
In practical terms, this solution brings three major improvements to Ethereum Rollups:
- Scalability: Flashblocks divide each 1-second block into 4 sub-blocks processed in parallel, allowing for 250ms block times and near-instant pre-confirmations.
- Guarantees and transparency: Since the rules are embedded within the TEE and cannot be altered, transactions are protected from sequencer manipulation, ensuring full transparency and better protection against MEV.
- MEV Internalization: The predictability and guaranteed execution of transactions allow applications to impose a tax on priority fees, reducing the incentive for MEV attacks while redistributing captured value to users (e.g., on Unichain, this benefits Uniswap liquidity providers).
Rollup-Boost was developed in collaboration with Uniswap Labs and OP Labs (Optimism) and was first deployed on Unichain, Uniswap's Layer 2 network. More recently, on February 27, Base announced the deployment of Flashblocks on its testnet, aiming to increase its network performance tenfold, already among the highest in the ecosystem.
How is Base Utilizing Flashblocks?
Base is currently the most popular Ethereum Layer 2 network, boasting nearly $3 billion in TVL and over one million daily active addresses. In a post on X (formerly Twitter), Base announced the implementation of Flashblocks on its testnet, with a mainnet integration planned for Q2 2025, positioning the network as "the fastest EVM chain to date, reducing effective block times from 2 seconds to 200 milliseconds."
Among the key benefits of Rollup-Boost, Base primarily highlighted scalability, reducing block times from 2 seconds to 0.2 seconds, resulting in transaction confirmations up to 10 times faster for users. As a result, transactions per second (TPS) are expected to increase from approximately 100 to over 500.
This integration significantly enhances Base’s scalability, while providing a superior user experience, with confirmation times twice as fast as its primary competitor in the ultra-high-performance blockchain sector: Solana.
Solana vs. Base: Can They Really Be Compared?
Base’s announcement of Flashblocks integration and its claim that the network would now be "twice as fast as Solana" sparked reactions within the crypto community. Mert, CEO of Helius, voiced concerns about using block time as a comparison metric.
He explained that Solana has a block time of 400ms but operates using a system of “shreds” (block fragments) that parallelize transactions at 15–20ms intervals. In fact, he pointed out that these shreds inspired the Flashblocks technology.
In comparison, Base will still have a 2-second block time but will rely on Flashblocks (similar to shreds), allowing for 250ms intervals between transactions. In other words, Mert argues that Solana could equally claim to have a “block time” of 15–20ms.
At the core of this debate is a simple issue: Base is a Layer 2, whereas Solana is a Layer 1. Solana’s 15–20ms shred intervals cannot be considered “block time” because they enable transaction parallelization. Since Solana is a Layer 1 with its own consensus mechanism, a full 400ms block time cycle is required to provide finality guarantees to users.
Conversely, as a Layer 2, Base does not require consensus finality and can offer what is known as “pre-confirmations.” These pre-confirmations guarantee with near certainty that a transaction will go through, while the use of TEEs ensures that execution rules remain enforced.
Thus, while the term “block time” is somewhat ambiguous in this discussion, the key takeaway is understanding when a user is guaranteed that their transaction has been processed or will be processed—what we call “confirmation” and “pre-confirmation.” In this regard, Base can indeed offer a 250ms “pre-confirmation,” whereas Solana requires 400ms for full confirmation.
Of course, this comparison also involves fundamental differences in security, trust, and decentralization, which are complex and difficult to assess objectively.
The Future of Rollup-Boost Technology
Upcoming Innovations
Through the examples of Base and Unichain, it is evident that Rollup-Boost is a highly customizable tool for blockchains. Base, focusing on scalability, has emphasized the speed advantages of Flashblocks, while Unichain, focused on DeFi, highlights the taxation and MEV advantages.
Flashbots has already announced several upcoming improvements that could further enhance the efficiency and security of Rollup-Boost, encouraging wider adoption among Ethereum Rollups:
- Encrypted mempool: Currently, only the block builder operates within the secure TEE environment. The next step is to encrypt transactions before execution, preventing front-running and mempool exploitation by malicious actors.
- TEE validity proofs: One of the biggest challenges for Rollups is achieving Stage 2 decentralization, a standard defining true security and decentralization for Layer 2s. Integrating a TEE-based prover could accelerate this transition.
- Co-processing for sequencers: This technology would allow sequencers to process transactions without relying on a single centralized entity, ensuring a more equitable execution environment for deployed applications.
- Multi-VM support: Currently designed for the EVM, Rollup-Boost could be expanded to other virtual machines, such as the SVM (Solana Virtual Machine) or Move (used by Aptos and Sui), enhancing interoperability across different blockchain ecosystems.
The Impact on Ethereum
The rapid advancement of Layer 2 scalability is progressively reshaping the dynamics among existing blockchain solutions. Rollups like Base, Unichain, and emerging networks like Eclipse and MegaETH are adopting strategies inspired by Solana to enhance performance while leveraging Ethereum’s security.
This trend toward increased bandwidth and reduced latency (IBRL) demonstrates that fast transaction execution is becoming a key factor in attracting users. The integration of Rollup-Boost across multiple EVM Layer 2s could significantly narrow the performance gap with Solana and other high-speed blockchains.
Additionally, MEV redistribution to applications is a critical aspect of this innovation. Unlike Solana’s new REV model (where MEV is redistributed to validators), Rollups leveraging Flashblocks can implement mechanisms that benefit end users and DeFi protocols.
Final Thoughts
If the promises of Flashblocks and Rollup-Boost are realized, Ethereum could soon see the emergence of ultra-fast EVM Layer 2s capable of competing with the market’s most high-performance blockchains.
Still, Flashbots, Uniswap Labs, and OP Labs are evolving this technology rapidly while staying true to Ethereum’s core values. As Ethereum continues to scale through modular architectures and Rollups, Rollup-Boost could play a crucial role in shaping the future of Ethereum’s Layer 2 ecosystem.
