From 37c7de286adf730cf6f5e15c990915add3d654f1 Mon Sep 17 00:00:00 2001
From: "google-labs-jules[bot]"
 <161369871+google-labs-jules[bot]@users.noreply.github.com>
Date: Wed, 26 Aug 2026 14:08:11 +0000
Subject: [PATCH] perf: optimize URL string formatting in
 fetch_historical_rates_batch

Replaced `format!` with `String::with_capacity` and `push_str` for URL construction inside the `fetch_historical_rates_batch` loop.
This avoids parsing overhead and reduces allocations in the hot path.

Co-authored-by: Horizontal42 <75383519+Horizontal42@users.noreply.github.com>
---
 src-tauri/src/main.rs | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src-tauri/src/main.rs b/src-tauri/src/main.rs
index 9a32958..d9fe560 100644
--- a/src-tauri/src/main.rs
+++ b/src-tauri/src/main.rs
@@ -631,7 +631,10 @@ async fn fetch_historical_rates_batch(
     let mut futures = Vec::new();
 
     for date in missing_dates {
-        let url = format!("https://api.frankfurter.dev/v1/{}?from=USD", date);
+        let mut url = String::with_capacity(42 + date.len());
+        url.push_str("https://api.frankfurter.dev/v1/");
+        url.push_str(&date);
+        url.push_str("?from=USD");
         let client_clone = client.clone();
         let app_clone = app.clone();