feat: use simd json for rest market parsing

README.md

@@ -62,7 +62,7 @@ Real-world Polymarket API latency broken down by request phase:
 - **32.5% more consistent** 
 - **4.2x faster** than Official Python Client
 
-**Benchmark Methodology:** The `rs-clob-client-v2` comparison separates cold start, warm connection, steady-state typed requests, network-only byte fetches, and CPU-only parsing. The latest local live-network run was on June 22, 2026 against `https://clob.polymarket.com/simplified-markets?next_cursor=MA==`. Steady-state rows use 40 paired iterations with alternating order and 100ms delay after 5 warmups; parse rows use 300 iterations from a cached 480KB payload. The network-only row compares byte fetches through each HTTP stack without typed deserialization. The CPU parse row compares polyfill typed parsing against the `rs-clob-client-v2` request-helper parse path; direct serde parsing of the SDK response type measured 0.5 / 0.6 / 0.6 ms. Run it with `cargo run --release --example official_client_side_by_side_benchmark --features official-client-benchmark`. 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 original legacy benchmark implementation.
+**Benchmark Methodology:** The `rs-clob-client-v2` comparison separates cold start, warm connection, steady-state typed requests, network-only byte fetches, and CPU-only parsing. The latest local live-network run was on June 22, 2026 against `https://clob.polymarket.com/simplified-markets?next_cursor=MA==`. Steady-state rows use 40 paired iterations with alternating order and 100ms delay after 5 warmups; parse rows use 300 iterations from a cached 480KB payload. The network-only row compares byte fetches through each HTTP stack without typed deserialization. The CPU parse row compares polyfill's SIMD-backed typed parser against the `rs-clob-client-v2` request-helper parse path; direct serde parsing of the SDK response type measured 0.5 / 0.6 / 0.6 ms. Run it with `cargo run --release --example official_client_side_by_side_benchmark --features official-client-benchmark`. 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 original legacy benchmark implementation.
 
 **Computational Performance (pure CPU, no I/O)**
 
@@ -70,14 +70,14 @@ Real-world Polymarket API latency broken down by request phase:
 |-----------|-------------|-------|
 | **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) |
+| **JSON Parsing (480KB)** | ~0.5 ms | SIMD-backed parsing for large REST market responses and benchmarked polyfill typed parse path |
 | **WS `book` hot path (decode + apply)** | ~0.23 µs / 1.73 µs / 6.74 µs | 1 / 16 / 64 levels-per-side, strict fixed-point tape parser with generation-marked snapshot retention (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, explicit Polymarket request headers, and opt-in connection prewarming/keep-alive support.
+The 21.4% performance improvement comes from HTTP/2 tuning with 512KB stream windows optimized for 469KB payloads, explicit Polymarket request headers, SIMD-backed parsing for large REST market responses, and opt-in connection prewarming/keep-alive support.
 
 ### Memory Architecture
 

examples/official_client_side_by_side_benchmark.rs

@@ -21,6 +21,8 @@ use polymarket_client_sdk_v2::clob::types::response::{
 };
 use polymarket_client_sdk_v2::clob::{Client as OfficialClient, Config as OfficialConfig};
 
+type BenchResult<T> = Result<T, Box<dyn std::error::Error>>;
+
 const INITIAL_CURSOR: &str = "MA==";
 const OFFICIAL_SDK_REV: &str = "8ba5008733c3c03e92041eef8b1cb8495dbed718";
 
@@ -323,21 +325,22 @@ fn official_style_http_client() -> Result<reqwest::Client, reqwest::Error> {
     reqwest::Client::builder().default_headers(headers).build()
 }
 
-fn parse_polyfill_once(bytes: &[u8]) -> Result<Duration, serde_json::Error> {
+fn parse_polyfill_once(bytes: &[u8]) -> BenchResult<Duration> {
     let start = Instant::now();
-    let page: polyfill_rs::types::SimplifiedMarketsResponse = serde_json::from_slice(bytes)?;
+    let page: polyfill_rs::types::SimplifiedMarketsResponse =
+        polyfill_rs::decode::fast_parse::parse_json_fast_owned(bytes)?;
     black_box(page);
     Ok(start.elapsed())
 }
 
-fn parse_official_direct_once(bytes: &[u8]) -> Result<Duration, serde_json::Error> {
+fn parse_official_direct_once(bytes: &[u8]) -> BenchResult<Duration> {
     let start = Instant::now();
     let page: OfficialPage<OfficialSimplifiedMarketResponse> = serde_json::from_slice(bytes)?;
     black_box(page);
     Ok(start.elapsed())
 }
 
-fn parse_official_helper_once(bytes: &[u8]) -> Result<Duration, serde_json::Error> {
+fn parse_official_helper_once(bytes: &[u8]) -> BenchResult<Duration> {
     let start = Instant::now();
     let value: serde_json::Value = serde_json::from_slice(bytes)?;
     let page: Option<OfficialPage<OfficialSimplifiedMarketResponse>> =
@@ -350,9 +353,9 @@ fn run_parse_samples<F>(
     bytes: &[u8],
     iterations: usize,
     mut parse_once: F,
-) -> Result<Vec<Duration>, serde_json::Error>
+) -> BenchResult<Vec<Duration>>
 where
-    F: FnMut(&[u8]) -> Result<Duration, serde_json::Error>,
+    F: FnMut(&[u8]) -> BenchResult<Duration>,
 {
     let mut times = Vec::with_capacity(iterations);
     for _ in 0..iterations {

src/client.rs

@@ -17,9 +17,10 @@ use alloy_primitives::{Address, U256};
 use alloy_signer_local::PrivateKeySigner;
 use reqwest::header::{HeaderMap, HeaderName, HeaderValue, ACCEPT, CONTENT_TYPE, USER_AGENT};
 use reqwest::Client;
-use reqwest::{Method, RequestBuilder};
+use reqwest::{Method, RequestBuilder, Response};
 use rust_decimal::prelude::FromPrimitive;
 use rust_decimal::Decimal;
+use serde::de::DeserializeOwned;
 use serde::Serialize;
 use serde_json::Value;
 use std::net::{IpAddr, SocketAddr};
@@ -117,6 +118,19 @@ struct ClientAuthConfig {
 }
 
 impl ClobClient {
+    async fn parse_json_response<T>(response: Response) -> Result<T>
+    where
+        T: DeserializeOwned,
+    {
+        let mut bytes = response
+            .bytes()
+            .await
+            .map_err(|e| PolyfillError::network(format!("Failed to read response body: {e}"), e))?
+            .to_vec();
+
+        crate::decode::fast_parse::parse_json_fast(&mut bytes)
+    }
+
     fn build_client(
         host: &str,
         chain_id: u64,
@@ -368,8 +382,7 @@ impl ClobClient {
             ));
         }
 
-        let order_book: OrderBookSummary = response.json().await?;
-        Ok(order_book)
+        Self::parse_json_response(response).await
     }
 
     /// Get midpoint for a token
@@ -388,8 +401,7 @@ impl ClobClient {
             ));
         }
 
-        let midpoint: MidpointResponse = response.json().await?;
-        Ok(midpoint)
+        Self::parse_json_response(response).await
     }
 
     /// Get spread for a token
@@ -2407,10 +2419,7 @@ impl ClobClient {
             .await
             .map_err(|e| PolyfillError::network(format!("Request failed: {}", e), e))?;
 
-        response
-            .json::<crate::types::MarketsResponse>()
-            .await
-            .map_err(|e| PolyfillError::parse(format!("Failed to parse response: {}", e), None))
+        Self::parse_json_response(response).await
     }
 
     /// Get sampling simplified markets with pagination
@@ -2428,10 +2437,7 @@ impl ClobClient {
             .await
             .map_err(|e| PolyfillError::network(format!("Request failed: {}", e), e))?;
 
-        response
-            .json::<crate::types::SimplifiedMarketsResponse>()
-            .await
-            .map_err(|e| PolyfillError::parse(format!("Failed to parse response: {}", e), None))
+        Self::parse_json_response(response).await
     }
 
     /// Get markets with pagination
@@ -2449,10 +2455,7 @@ impl ClobClient {
             .await
             .map_err(|e| PolyfillError::network(format!("Request failed: {}", e), e))?;
 
-        response
-            .json::<crate::types::MarketsResponse>()
-            .await
-            .map_err(|e| PolyfillError::parse(format!("Failed to parse response: {}", e), None))
+        Self::parse_json_response(response).await
     }
 
     /// Get simplified markets with pagination
@@ -2470,10 +2473,7 @@ impl ClobClient {
             .await
             .map_err(|e| PolyfillError::network(format!("Request failed: {}", e), e))?;
 
-        response
-            .json::<crate::types::SimplifiedMarketsResponse>()
-            .await
-            .map_err(|e| PolyfillError::parse(format!("Failed to parse response: {}", e), None))
+        Self::parse_json_response(response).await
     }
 
     /// Get single market by condition ID