In-depth essays · #18 / 50 · Wallets, Oracles, Security & Payments
Parallel EVM and Real-Time Blockchains: Inside the Speed Race of Monad, Sei, and MegaETH
How optimistic parallel execution, custom state databases, and 10ms mini-blocks break sequential bottlenecks
For a decade, the Ethereum Virtual Machine processed every transaction inside a block strictly one by one on a single thread. Newer high-throughput chains in Ethereum City—Monad, Sei, and MegaETH—keep full EVM compatibility while re-engineering the execution engine underneath.
1. Why Sequential Execution Left Multi-Core CPUs Idle
If Alice sends USDC to Bob while Carol mints an NFT in an unrelated contract, the two transactions touch completely separate storage slots. Yet traditional EVM clients execute them one after the other, leaving modern multi-core CPUs underutilized.
2. Optimistic Parallel Execution: Run Together, Re-Execute Only Conflicts
Monad and Sei v2 use optimistic parallel execution: transactions run concurrently across multiple cores, and the engine checks afterward whether any two transactions read and wrote the same storage slot. Non-conflicting transactions commit immediately, while conflicting ones re-run in canonical order—producing the exact same final state as sequential EVM execution.
3. Solving the Real Bottleneck—State Disk I/O and 10ms In-Memory Sequencing
Because reading Merkle Patricia Trie state from SSDs is often slower than CPU execution itself, Monad built a custom asynchronous state database (MonadDB) alongside pipelined 0.4-second consensus, while MegaETH holds working state in RAM on a high-spec sequencer to stream 10-millisecond mini-blocks.
4. Watching High-Throughput Roads in Ethereum City
Compare the ring roads of MegaETH in the western L2 quarter with the southeastern harbor islands of Monad, Sei, Sonic, and HyperEVM to see how parallel execution and fast finality translate into live road traffic.
Related districts in the city
Related glossary terms
This essay is an explainer written to help you read the city; it is not investment advice. Facts on this page are as of 2026-10 and may change. If you spot a mistake, please tell us through the contact page.