Ouroboros Leios: A transformative upgrade that aims to redefine Cardano’s scalability

For so long, blockchain scalability has been a zero-sum game, and increasing throughput could pose the risk of compromising decentralization or security. However, Cardano is pushing the limits through the introduction of the new blockchain model Leios. This development introduces a parallelized architecture with three different block types: input, endorser, and ranking blocks. These block types enable simultaneous transaction processing while ensuring node accessibility and cryptographic rigor. The implications of this upgrade are profound for investors, redefining the approach to growth through a blockchain that scales while maintaining its foundational principles.

Leios is a revolutionary development for the Cardano ecosystem, paving the way for advanced decentralized finance, global decentralized application infrastructure, and mass adoption, all while maintaining the decentralization and security that define Cardano.  While this upgrade is still under review, if all goes well, it could significantly impact ada price prediction for the future and set a new standard for the performance of Cardano.

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Optimizing Ouroboros for greater scalability and efficiency

The Ouroboros family of protocols has expanded Cardano’s capabilities over time, with each iteration built upon peer-reviewed research to improve decentralization, security, and efficiency. While these developments have positioned the blockchain as scientifically grounded, further throughput upgrades are needed to accommodate the growth of the user base.

The Ouroboros Praos, the current version of the protocol, isn’t limited by node resources, such as CPU performance or network capacity. Instead, the throughput is constrained by the underlying data of the consensus algorithm and the communication dependencies, which need to be addressed through a fundamentally new design that can enable additional network capacity without compromising the security properties of Cardano. Ouroboros Leios aims to achieve precisely that, marking a major milestone for Cardano.

The purpose of Ouroboros Leios

Notably, Leios aims to introduce a new concurrent blockchain structure by leveraging underutilized network and computational resources. Currently, the Ouroboros Praos faces challenges in throughput, not due to hardware limitations, but because of inherent inefficiencies in the blockchain algorithm. In Praos, block diffusion takes up a fraction of the entire block time. On Cardano’s mainnet, blocks are created every 20 seconds on average, although it can vary, and sometimes, two blocks can be created only seconds apart or in the same slot. Given that block diffusion occurs in approximately five seconds, the system is idle for nearly 75% of the time, with the 20-second interval allowing sufficient time for propagation. This helps maintain reasonable confirmation speeds while decreasing forking risks.

Another challenge is that during block diffusion, nodes generally remain idle, with only those actively processing a block using their network resources, which occurs sequentially as blocks propagate through the network. Ouroboros Leios aims to address these inefficiencies by redesigning the consensus algorithm and the blockchain's structure. Its primary goals include the following:

• Increase data throughput: currently, Cardano has a throughput of about 4.4 kB/s; however, a server would typically have the capacity to handle about 900 kB/s per peer.
• Increase script throughput: Currently, Cardano's script throughput is approximately 2 ms/s, while a single CPU core provides 1,000 ms/s.
• Enhance transaction throughput: This measure is based on the throughput of data and scripts. According to simulation tools, Ouroboros Leios could provide targets of more than 1,000 transactions per second by leveraging node parallelism.
• Ensure robust security: Achieve high throughout while maintaining the security properties of the other Ouroborus versions.
• Maintain decentralization: Ensure the protocol's efficiency without compromising its security properties or decentralization.

Addressing censorship resistance

Notably, Leios addresses a core censorability issue that has deterred some applications from being developed on the Cardano blockchain. To be more specific, when the Cardano network is under a major load, it becomes difficult to process time-sensitive transactions on-chain. As the protocol matures and alternative node implementations emerge, people will deploy nodes with custom prioritization rules for transactions. The main issue is that Cardano charges for used capacity, which increases linearly – an 8kB block utilizes 8kB, regardless of whether the chain is under load or not.

With Ouroboros Praos, there’s very little that can be done to address this problem, as it is difficult to design a fair protocol that charges considerably for that depleting resource, and at the same time, that capacity cannot be increased dramatically. Notably, dApps compete with each other to occupy that block space, and even with a few of them, the user experience considerably degrades when the Cardano blockchain is under load. This has been a concern for many teams assessing whether to deploy on Cardano, and in some instances, it has even driven them away entirely.

Leios is valuable not in the sense that it enables a single dApp to scale to numerous transactions per second, but because it allows thousands of dApps to coexist peacefully, which makes a huge difference when it comes to the broad adoption of a blockchain. By providing a scalable capacity, Leios ensures that anyone can expect their transactions to be on-chain throughout a wider range of chain conditions. There are, obviously, risks that shouldn’t be overlooked. For example, if the demands are higher resource, this could strain smaller nodes, potentially leading to centralization of validation. Meanwhile, the 1-1.5 year deployment timeline for the protocol means that competitors could outpace the project in short-term scalability benchmarks. However, for Cardano, which has prioritized detailed research over hype throughout the years, these trade-offs indicate a calculated strategy to prevent the drawbacks of “speed at all costs”.

Takeaway

Ouroboros Leios is more than a protocol upgrade for Cardano – it represents a fundamental redesign that aims to unlock scalability without compromising the blockchain's commitment to security and decentralization. While the approach is not without risks, Leios signals a research-driven path forward. Instead of chasing short-term benchmarks, Cardano is building a system that can resist censorship, scale sustainably, and deliver predictable user experiences under heavy load.

If successfully implemented, the upgrade could strengthen Cardano's position as one of the platforms capable of offering high throughput alongside robust security and decentralization.

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