Polymarket tests Rust-based Nex ahead of possible December launch

Vice president of engineering for DeFi Josh Stevens announced the sandbox on X on Nov. 13. Nex had spent the previous week running alongside Polymarket’s existing exchange, mirroring production orders so engineers can compare speed, stability under load and matching accuracy. The company says requests and responses will remain compatible for market makers and developers.

Polymarket’s current central limit order book handles 10,000 commands per second under steady load and 15,000 in short bursts, according to figures Stevens published. Nex is designed for 100,000 and 150,000, respectively. These are command rates—covering actions such as placing or canceling orders—not completed trades per second. Stevens said further optimization could raise capacity to 200,000 commands per second, with bursts of 250,000. A larger rewrite could eventually reach 1 million, though he said that level is not currently needed.

Internal benchmarks show Nex’s p99 order-placement time at 3.76 milliseconds, compared with 1.55 seconds on the existing system. The p99 figures for canceling orders were 3.20 milliseconds versus 627.92 milliseconds; for canceling market orders, 5.14 milliseconds versus 810.16 milliseconds. Stevens cautioned that these are internal exchange timings, not end-to-end measurements of a trader’s full request and response. At p95, order placement fell from 341.84 milliseconds to 1.59 milliseconds.

Nex also changes how requests to cancel all open orders are handled: it acknowledges them only after every order has been canceled. Stevens put Nex’s p99 completion time at 3.14 milliseconds, against roughly 0.64 to 2.04 seconds for the existing system’s full process. A rewritten Rust WebSocket service, which distributes order-book changes, prices and fills, recorded p99 write latency of 0.099 milliseconds, compared with 44.5 to 88.1 milliseconds previously. Those feed improvements can be released separately and may arrive before the exchange transition. The rewrite began in August; the team left some optimizations for later work, which Stevens said would start in the first quarter of next year, with a target of making p95 and p99 timings another five times faster.