diff --git a/.jules/bolt.md b/.jules/bolt.md
new file mode 100644
index 0000000..6de79a9
--- /dev/null
+++ b/.jules/bolt.md
@@ -0,0 +1,3 @@
+## YYYY-MM-DD - [PacketType.classify Optimization]
+**Learning:** `PacketType.classify` is a small, frequently called utility function on the hot path (packet classification). In Zig, marking such functions with `inline` ensures the compiler eliminates function call overhead across module boundaries. Also, standard `switch` statements on integers compile to jump tables. Extracting the dominant case (data-plane packets, type 4) into an explicit `if` branch before the `switch` improves branch prediction and avoids jump table overhead.
+**Action:** I will add the `inline` keyword to `PacketType.classify` and add an explicit fast-path `if` check for `wg_transport` (type 4) before the `switch` statement in `src/wireguard/device.zig`. I will also add the `/// Optimization:` comment.
diff --git a/src/wireguard/device.zig b/src/wireguard/device.zig
index bfbf740..7e7b4c4 100644
--- a/src/wireguard/device.zig
+++ b/src/wireguard/device.zig
@@ -24,16 +24,20 @@ pub const PacketType = enum {
     stun, // STUN binding response
     unknown,
 
-    pub fn classify(data: []const u8) PacketType {
+    /// Optimization: inline function and extract dominant case (data-plane packets) into an explicit fast-path to improve branch prediction and avoid jump table overhead.
+    pub inline fn classify(data: []const u8) PacketType {
         if (data.len < 4) return .unknown;
 
         // WireGuard messages: first byte is type, next 3 are zeros
         const msg_type = std.mem.readInt(u32, data[0..4], .little);
+
+        // Fast path for transport data (most common)
+        if (msg_type == 4) return .wg_transport;
+
         return switch (msg_type) {
             1 => .wg_handshake_init,
             2 => .wg_handshake_resp,
             3 => .wg_cookie,
-            4 => .wg_transport,
             else => blk: {
                 // STUN: check for magic cookie at bytes 4-7
                 if (data.len >= 8) {