From 24d28e27c6662a39f3ceba7b8a77965cd10a0c74 Mon Sep 17 00:00:00 2001
From: lassidevs <lassi.koivisto7@gmail.com>
Date: Tue, 28 Oct 2025 22:57:54 +0200
Subject: [PATCH 1/2] fix: typo

---
 README.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 7166c0a..2c6df1c 100644
--- a/README.md
+++ b/README.md
@@ -121,7 +121,7 @@ cargo build
 fastly compute publish
 ```
 
-## Devleopment
+## Development
 
 #### Install viceroy for running tests
 ```sh

From 1f653123791f3ed9dcb5f8eab185fedc4ca6230e Mon Sep 17 00:00:00 2001
From: lassidevs <lassi.koivisto7@gmail.com>
Date: Tue, 28 Oct 2025 23:58:33 +0200
Subject: [PATCH 2/2] feat: optimize handlebars with lazy globals

Use a thread-safe OnceLock to lazily initialize and cache the global
Handlebars renderer
---
 crates/common/src/synthetic.rs | 27 +++++++++++++++++++++------
 1 file changed, 21 insertions(+), 6 deletions(-)

diff --git a/crates/common/src/synthetic.rs b/crates/common/src/synthetic.rs
index b62ec8c..83b7f0d 100644
--- a/crates/common/src/synthetic.rs
+++ b/crates/common/src/synthetic.rs
@@ -10,6 +10,7 @@ use handlebars::Handlebars;
 use hmac::{Hmac, Mac};
 use serde_json::json;
 use sha2::Sha256;
+use std::sync::OnceLock;
 
 use crate::constants::{HEADER_SYNTHETIC_PUB_USER_ID, HEADER_SYNTHETIC_TRUSTED_SERVER};
 use crate::cookies::handle_request_cookies;
@@ -18,6 +19,18 @@ use crate::settings::Settings;
 
 type HmacSha256 = Hmac<Sha256>;
 
+static HANDLEBARS: OnceLock<Handlebars<'static>> = OnceLock::new();
+
+/// Returns a global, lazily initialized `Handlebars` instance.
+fn handlebars(hb_template: &str) -> &'static Handlebars<'static> {
+    HANDLEBARS.get_or_init(|| {
+        let mut hbs = Handlebars::new();
+        hbs.register_template_string("synthetic_id", hb_template)
+            .expect("Failed to register synthetic ID template at startup");
+        hbs
+    })
+}
+
 /// Generates a fresh synthetic ID based on request parameters.
 ///
 /// Creates a deterministic ID using HMAC-SHA256 with the configured secret key
@@ -50,7 +63,8 @@ pub fn generate_synthetic_id(
         .and_then(|h| h.to_str().ok())
         .map(|lang| lang.split(',').next().unwrap_or("unknown"));
 
-    let handlebars = Handlebars::new();
+    let handlebars = handlebars(&settings.synthetic.template);
+
     let data = &json!({
         "client_ip": client_ip.unwrap_or("unknown".to_string()),
         "user_agent": user_agent.unwrap_or("unknown"),
@@ -60,11 +74,12 @@ pub fn generate_synthetic_id(
         "accept_language": accept_language.unwrap_or("unknown")
     });
 
-    let input_string = handlebars
-        .render_template(&settings.synthetic.template, data)
-        .change_context(TrustedServerError::Template {
-            message: "Failed to render synthetic ID template".to_string(),
-        })?;
+    let input_string =
+        handlebars
+            .render("synthetic_id", data)
+            .change_context(TrustedServerError::Template {
+                message: "Failed to render synthetic ID template".to_string(),
+            })?;
 
     log::info!("Input string for fresh ID: {} {}", input_string, data);