ZCLS: A Lifecycle Strategy for Efficient ZK-Rollup Circuit Optimization in Circom

Abstract

Scalability remains a key challenge for layer 1 blockchains. ZK-Rollups, leveraging zero-knowledge proofs, offer a promising layer 2 solution by improving throughput and reducing costs while preserving security. However, the performance of ZK-Rollup still poses a major barrier to practical implementation. The proving circuits in popular applications like ERC-20 transactions are highly complex, often containing a large number of constraints, which directly impacts the computation time and resources required to generate zero-knowledge proofs. This study presents an empirical study on the impact of constraint optimization in Circom on the performance of ERC-20 ZK-Rollups using Groth16. Three optimization levels (–O0, –O1, –O2) are evaluated across transaction batches ranging from 4 to 128, with further exploration up to 512 for specific optimization levels to assess scalability. Results show a trade-off: –O2 reduces constraints by up to 73.2% but increases compilation time by 213.35% at batch size 128, while –O1 offers a more balanced approach suitable for development stages. Findings confirm that proof generation time is closely tied to constraint count and complexity. Based on these insights, this study introduces ZCLS (ZK-Circuit Lifecycle Strategy), a practical framework for selecting optimization flags aligned with development stages to enhance ZK-Rollup system efficiency.