Binance BBO bench, please beat my tweet if

// BENCH

const NEW_TEMPLATE_INPUT: &str = r#"{"e":"depthUpdate","E":1571889248277,"T":1571889248276,"s":"BTCUSDT","U":390497796,"u":390497878,"pu":390497794,"b":[["7403.89","0.002"],["7403.90","3.906"],["7404.00","1.428"],["7404.85","5.239"],["7405.43","2.562"]],"a":[["7405.96","3.340"],["7406.63","4.525"],["7407.08","2.475"],["7407.15","4.800"],["7407.20","0.175"]]}"#;

fn criterion_benchmark(c: &mut Criterion) {
    c.bench_function("Deserialize using serde", |b| {
        b.iter(|| {
            let _: BBO =
                serde_json::from_str(NEW_TEMPLATE_INPUT).expect("Failed to deserialize JSON");
        })
    });

    c.bench_function("Deserialize without serde", |b| {
        b.iter(|| {
            // Your function should go here
        })
    });

}

criterion_group!(benches, criterion_benchmark);
criterion_main!(benches);

// Serde de

#[derive(Debug)]
pub struct BBO {
    pub bid: (f64, f64),
    pub ask: (f64, f64),
}

impl<'de> Deserialize<'de> for BBO {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
        D: Deserializer<'de>,
    {
        #[derive(Deserialize)]
        struct DepthUpdate {
            #[serde(alias = "b")]
            bid: Vec<Vec<String>>,
            #[serde(alias = "a")]
            ask: Vec<Vec<String>>,
        }

        let depth_update = DepthUpdate::deserialize(deserializer)?;

        // Assuming the best bid and ask are the first elements in the bid and ask vectors
        let bid = depth_update
            .bid
            .get(0)
            .ok_or_else(|| de::Error::missing_field("bid"))?;
        let ask = depth_update
            .ask
            .get(0)
            .ok_or_else(|| de::Error::missing_field("ask"))?;

        let bid_tuple = (
            bid[0].parse::<f64>().map_err(de::Error::custom)?,
            bid[1].parse::<f64>().map_err(de::Error::custom)?,
        );

        let ask_tuple = (
            ask[0].parse::<f64>().map_err(de::Error::custom)?,
            ask[1].parse::<f64>().map_err(de::Error::custom)?,
        );

        Ok(BBO {
            bid: bid_tuple,
            ask: ask_tuple,
        })
    }
}