[](https://crates.io/crates/polyfill2)
[](https://docs.rs/polyfill2)
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A high-performance Rust client for Polymarket's **CLOB V2** API, with latency-optimized data structures and zero-allocation hot paths. This is a V2 migration fork of [`polyfill-rs`](https://github.com/floor-licker/polyfill-rs) (Julius Tranquilli), updated in April 2026 for the CLOB V2 cutover (new EIP-712 Order schema, new contract addresses, new endpoint URLs, new WebSocket message shapes).
`polyfill-rs` was originally created as a performance-focused Rust alternative to `polymarket-rs-client`, aiming to beat the benchmarks quoted in that project's README while maintaining zero-allocation hot paths. This fork carries those properties forward onto V2.
**On zero-alloc**: in this project, "zero-alloc" means zero allocations in the per-message handling loop after init/warm-up — i.e. **the hot path never touches the heap**, even though cold paths do. Order book paths that introduce new allocations by design:
- First time seeing a token/book (HashMap insert + key clone): `src/book.rs:~788`
- New price levels (BTreeMap node growth): `src/book.rs:~409`
## Quick Start
Add to your `Cargo.toml`:
```toml
[dependencies]
polyfill2 = "0.1"
```
```rust
use polyfill2::{ClobClient, Side, OrderType};
#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
let client = ClobClient::new("https://clob-v2.polymarket.com");
let markets = client.get_sampling_markets(None).await?;
println!("Found {} markets", markets.data.len());
Ok(())
}
```
## Performance Comparison
> **Note:** the numbers below were measured on upstream `polyfill-rs` against CLOB V1 (`clob.polymarket.com`) prior to the V2 migration. Computational paths (book updates, spread/mid, WS decode) are unchanged and should still hold; the networked end-to-end number has not been re-measured against V2 — [#1](https://github.com/onsails/polyfill2-rs/issues/1) tracks re-measurement.
**Real-World API Performance (with network I/O)**
End-to-end performance with Polymarket's API, including network latency, JSON parsing, and decompression:
| **Fetch Markets** | **321.6 ms ± 92.9 ms** | 409.3 ms ± 137.6 ms | 1.366 s ± 0.048 s |
**Performance vs polymarket-rs-client:**
- **21.4% faster**
- **32.5% more consistent**
- **4.2x faster** than Official Python Client
**Benchmark Methodology:** All benchmarks run side-by-side on the same machine, same network, same time using 20 iterations, 100ms delay between requests, /simplified-markets endpoint. Best performance achieved with connection keep-alive enabled. See `examples/side_by_side_benchmark.rs` in commit `a63a170`: https://github.com/floor-licker/polyfill-rs/blob/a63a170/examples/side_by_side_benchmark.rs for the complete benchmark implementation.
**Computational Performance (pure CPU, no I/O)**
| **Order Book Updates (1000 ops)** | 159.6 µs ± 32 µs | 6,260 updates/sec, zero-allocation |
| **Spread/Mid Calculations** | 70 ns ± 77 ns | 14.3M ops/sec, optimized BTreeMap |
| **JSON Parsing (480KB)** | ~2.3 ms | SIMD-accelerated parsing (1.77x faster than serde_json) |
| **WS `book` hot path (decode + apply)** | ~0.28 µs / 2.01 µs / 7.70 µs | 1 / 16 / 64 levels-per-side, ~3.7–4.0x faster vs serde decode+apply (see `benches/ws_hot_path.rs`) |
Run the WS hot-path benchmark locally with `cargo bench --bench ws_hot_path`.
**Key Performance Optimizations:**
The 21.4% performance improvement comes from SIMD-accelerated JSON parsing (1.77x faster than serde_json), HTTP/2 tuning with 512KB stream windows optimized for 469KB payloads, integrated DNS caching, connection keep-alive, and buffer pooling to reduce allocation overhead.
### Memory Architecture
Pre-allocated pools eliminate allocation latency spikes. Configurable book depth limiting prevents memory bloat. Hot data structures group frequently-accessed fields for cache line efficiency.
### Architectural Principles
Price data converts to fixed-point at ingress boundaries while maintaining tick-aligned precision. The critical path uses integer arithmetic with branchless operations. Data converts back to IEEE 754 at egress for API compatibility. This enables deterministic execution with predictable instruction counts.
### Measured Network Improvements
| **Optimized HTTP client** | **11% baseline improvement** | Every API call |
| **Connection pre-warming** | **70% faster subsequent requests** | Application startup |
| **Request parallelization** | **200% faster batch operations** | Multi-market data fetching |
| **Circuit breaker resilience** | **Better uptime during instability** | Production trading systems |
## Credits
`polyfill-rs` was originally authored by Julius Tranquilli ([floor-licker/polyfill-rs](https://github.com/floor-licker/polyfill-rs)). This V2 fork (`polyfill2`) is maintained by [onsails](https://github.com/onsails).