perf: simplify first letter capitalization

src/desktop.rs

@@ -1,21 +1,13 @@
 pub fn get_desktop_info() -> String {
-    fn capitalize_first_letter(s: &str) -> String {
-        if s.is_empty() {
-            return String::new();
-        }
-
-        let mut chars = s.chars();
-        let first_char = chars.next().unwrap().to_uppercase().to_string();
-        let rest: String = chars.collect();
-        first_char + &rest
-    }
-
     // Retrieve the environment variables and handle Result types
     let desktop_env = std::env::var("XDG_CURRENT_DESKTOP");
     let display_backend_result = std::env::var("XDG_SESSION_TYPE");
 
     // Capitalize the first letter of the display backend value
-    let display_backend = capitalize_first_letter(display_backend_result.as_deref().unwrap_or(""));
+    let mut display_backend = display_backend_result.unwrap_or_default();
+    if let Some(c) = display_backend.as_mut_str().get_mut(0..1) {
+        c.make_ascii_uppercase();
+    }
 
     // Trim "none+" from the start of desktop_env if present
     // Use "Unknown" if desktop_env is empty or has an error
@@ -26,10 +18,11 @@ pub fn get_desktop_info() -> String {
 
     // Handle the case where display_backend might be empty after capitalization
     let display_backend = if display_backend.is_empty() {
-        "Unknown".to_string()
+        "Unknown"
     } else {
-        display_backend
+        &display_backend
-    };
+    }
+    .to_string();
 
     format!("{desktop_env} ({display_backend})")
 }