diff --git a/easytier-core/src/tunnels/stats.rs b/easytier-core/src/tunnels/stats.rs
index c0680bcc..9765570f 100644
--- a/easytier-core/src/tunnels/stats.rs
+++ b/easytier-core/src/tunnels/stats.rs
@@ -1,9 +1,12 @@
-use std::sync::atomic::{AtomicU32, AtomicU64};
+use std::sync::atomic::{AtomicU32, AtomicU64, Ordering::Relaxed};
 
 pub struct WindowLatency {
     latency_us_window: Vec<AtomicU32>,
     latency_us_window_index: AtomicU32,
-    latency_us_window_size: AtomicU32,
+    latency_us_window_size: u32,
+
+    sum: AtomicU32,
+    count: AtomicU32,
 }
 
 impl WindowLatency {
@@ -11,39 +14,32 @@ impl WindowLatency {
         Self {
             latency_us_window: (0..window_size).map(|_| AtomicU32::new(0)).collect(),
             latency_us_window_index: AtomicU32::new(0),
-            latency_us_window_size: AtomicU32::new(window_size),
+            latency_us_window_size: window_size,
+
+            sum: AtomicU32::new(0),
+            count: AtomicU32::new(0),
         }
     }
 
     pub fn record_latency(&self, latency_us: u32) {
-        let index = self
-            .latency_us_window_index
-            .fetch_add(1, std::sync::atomic::Ordering::Relaxed);
-        let index = index
-            % self
-                .latency_us_window_size
-                .load(std::sync::atomic::Ordering::Relaxed);
-        self.latency_us_window[index as usize]
-            .store(latency_us, std::sync::atomic::Ordering::Relaxed);
+        let index = self.latency_us_window_index.fetch_add(1, Relaxed);
+        if index < self.latency_us_window_size {
+            self.count.fetch_add(1, Relaxed);
+        }
+
+        let index = index % self.latency_us_window_size;
+        let old_lat = self.latency_us_window[index as usize].swap(latency_us, Relaxed);
+
+        if old_lat < latency_us {
+            self.sum.fetch_add(latency_us - old_lat, Relaxed);
+        } else {
+            self.sum.fetch_sub(old_lat - latency_us, Relaxed);
+        }
     }
 
     pub fn get_latency_us<T: From<u32> + std::ops::Div<Output = T>>(&self) -> T {
-        let window_size = self
-            .latency_us_window_size
-            .load(std::sync::atomic::Ordering::Relaxed);
-        let mut sum = 0;
-        let mut count = 0;
-        for i in 0..window_size {
-            if i >= self
-                .latency_us_window_index
-                .load(std::sync::atomic::Ordering::Relaxed)
-            {
-                break;
-            }
-            sum += self.latency_us_window[i as usize].load(std::sync::atomic::Ordering::Relaxed);
-            count += 1;
-        }
-
+        let count = self.count.load(Relaxed);
+        let sum = self.sum.load(Relaxed);
         if count == 0 {
             0.into()
         } else {
@@ -72,32 +68,28 @@ impl Throughput {
     }
 
     pub fn tx_bytes(&self) -> u64 {
-        self.tx_bytes.load(std::sync::atomic::Ordering::Relaxed)
+        self.tx_bytes.load(Relaxed)
     }
 
     pub fn rx_bytes(&self) -> u64 {
-        self.rx_bytes.load(std::sync::atomic::Ordering::Relaxed)
+        self.rx_bytes.load(Relaxed)
     }
 
     pub fn tx_packets(&self) -> u64 {
-        self.tx_packets.load(std::sync::atomic::Ordering::Relaxed)
+        self.tx_packets.load(Relaxed)
     }
 
     pub fn rx_packets(&self) -> u64 {
-        self.rx_packets.load(std::sync::atomic::Ordering::Relaxed)
+        self.rx_packets.load(Relaxed)
     }
 
     pub fn record_tx_bytes(&self, bytes: u64) {
-        self.tx_bytes
-            .fetch_add(bytes, std::sync::atomic::Ordering::Relaxed);
-        self.tx_packets
-            .fetch_add(1, std::sync::atomic::Ordering::Relaxed);
+        self.tx_bytes.fetch_add(bytes, Relaxed);
+        self.tx_packets.fetch_add(1, Relaxed);
     }
 
     pub fn record_rx_bytes(&self, bytes: u64) {
-        self.rx_bytes
-            .fetch_add(bytes, std::sync::atomic::Ordering::Relaxed);
-        self.rx_packets
-            .fetch_add(1, std::sync::atomic::Ordering::Relaxed);
+        self.rx_bytes.fetch_add(bytes, Relaxed);
+        self.rx_packets.fetch_add(1, Relaxed);
     }
 }