Introduction
This comprehensive analysis explores Ethereum Layer 2 (L2) solutions through the lens of scalability, focusing on transaction fees and maximum achievable Transactions Per Second (TPS).
Key Insights
- Layer 2 Growth: L2 solutions address Ethereum's scalability issues by offering low fees and high throughput while inheriting Ethereum’s security.
- Focus Areas: Research covers 15 Universal Rollups and Optimium projects, emphasizing fee structures and TPS performance.
- Upcoming Upgrades: Ethereum’s EIP-4844 (proto-dank sharding) is expected to significantly reduce rollup costs.
Fee Structures in Rollups
Transaction Fee Components
Rollup fees comprise two primary elements:
- Execution Fee: Cost for processing L2 transactions (similar to Ethereum’s gas model).
- Data Fee (Rollup Fee): Cost for posting transaction data to Ethereum (calldata).
Fee Comparison Across Projects
| Project Type | Avg ETH Transfer Fee | Notable Features |
|--------------------|----------------------|------------------------------------------|
| OP Stack | Lowest | Intuitive fee model; leverages zlib compression. |
| ZK Rollups | Higher | Includes ZK proof generation costs. |
| Optimium | Cheapest | Avoids L1 calldata costs via off-chain DA. |
Bridge Costs:
- Deposits: Optimized in OP Stack projects like Base and Kroma.
- Withdrawals: Starknet and zkSync subsidize costs, while Optimistic Rollups enforce 7-day challenge periods.
Maximum TPS Analysis
Methodology
Max TPS is calculated as:
Max TPS = (Max L2 transactions per batch) / (Minimum batch interval)Project-Specific TPS
| Project | Max TPS | Key Constraints |
|------------------|---------|------------------------------------------|
| OP Stack | 455–714 | Batch interval: 2–6 seconds. |
| zkSync Era | 750 | High compression; 1-second batch interval.|
| Starknet | 25 | Focus on proof performance over EVM compatibility. |
| Scroll | 50 | Batch creation cycle: 10 seconds. |
Optimium (Metis, Mantle):
- Achieves 350–400 TPS by posting state roots to L1 and bulk data to off-chain DA layers.
Future Optimizations
- EIP-4844: Blob data transactions will reduce L1 calldata costs by ~90%.
- Sequencer Decentralization: Mitigates bottlenecks in batch validation.
FAQs
1. Why do ZK Rollups have higher fees than Optimistic Rollups?
ZK Rollups incur additional costs for generating and verifying cryptographic proofs, whereas Optimistic Rollups rely on fraud proofs with lower computational overhead.
2. How does EIP-4844 improve L2 scalability?
By introducing blob storage, EIP-4844 creates a separate fee market for data, drastically reducing the cost of posting batches to Ethereum.
3. What limits the max TPS of rollups?
The primary bottleneck is the batch submission frequency to L1. Even with fast L2 block production, TPS is constrained by Ethereum’s block space and proof verification times.
👉 Explore more about Ethereum scaling solutions
Conclusion
While rollups already offer 10x cheaper fees than Ethereum, their throughput is limited by L1 dependencies. Innovations like EIP-4844 and decentralized sequencers are poised to unlock further scalability.
About Kroma: An Optimistic Rollup transitioning to ZK Rollup via Tachyon.
👉 Join the Kroma ecosystem | Visit our GitHub
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