Analysis: After Istanbul upgrade, Ethereum's theoretical maximum TPS is 2048, but a new bottleneck has emerged

According to foreign media news today, iden3, a blockchain-based identity management solution company, recently released analysis results of testing Ethereum blockchain transaction throughput before and after the Istanbul upgrade and ZKRollup.

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The analysis concluded that after the Istanbul upgrade, using ZKRollup, Ethereum can theoretically handle a maximum of 2048 tps, which is lower than Ethereum developer Eric Conner’s requirement of 3000 tps, but still higher than VISA’s 2000 tps. Before the upgrade, Ethereum could only process 30 transactions per second.

Istanbul’s upgrade brings two Ethereum Improvement Proposals (EIPs) – EIP-1108 (making zk-SNARKs cheaper by re-pricing gas) and EIP-2028 (reducing the gas cost of calling data from 68 gas per byte to 16 gas per byte). Previously, it cost 21,000 gas to send a transaction on the Ethereum blockchain, ZKRollup reduced the cost to only 945 gas, and Istanbul further reduced it to only 300 gas.

The analysis also warns that the mentioned 2048 tps is merely a theoretical maximum, adding that in reality, things are not that simple. A throughput of 2048 tps would require batching 15 transactions into a single block, with a batch creation time of just one second (assuming a 15-second block time). The iden3 team also talked about how each zkRollup batch requires a short cryptographic proof (zk-SNARK) to prove the integrity of the transactions in that batch. The company also explained how generating this proof is computationally very expensive, adding that this is the main bottleneck to reaching the theoretical throughput limit.

“Currently, you can imagine that using one CPU and three GPUs, it takes us several minutes to generate a proof like this.”

Even putting aside the bottleneck of this proof generation, setting up a server capable of processing 2,000 transactions per second is not an easy task. According to analysis, just to process all the information, an advanced block explorer is required. As Ethereum developers continue to build the network, parallelization may be achieved in the future, shortening the proof generation time and keeping the cost reasonable.