Ethereum co-founder Vitalik Buterin has introduced a new metric for evaluating the performance of zero-knowledge proofs (ZK) and fully homomorphic encryption (FHE) technologies. Speaking on October 18, 2025, Buterin suggested using an 'efficiency ratio'—the ratio of encrypted computation time to original computation time—as a more practical alternative to the traditional 'operations per second' metric. This new approach is hardware-independent and highlights the efficiency cost of encryption technologies, enabling developers to make straightforward estimates based on known computation times. Buterin acknowledged that the efficiency ratio has limitations, particularly due to variations in SIMD/parallelization and memory access patterns. Despite these challenges, he believes the metric provides valuable insights into the performance of encryption technologies.