⚡ Bolt: Optimize terminal scrollback search with ASCII fast-path

crates/forktty-ui-gtk/src/gtk_app/terminal_search.rs

@@ -74,12 +74,26 @@ fn for_each_char_match_start(
     if needle.is_empty() {
         return;
     }
+    // ⚡ Bolt: Fast path for case-insensitive search.
+    // Hoist target character's ASCII lower/upper conversions outside the loop.
+    // If the haystack character is ASCII, we can directly compare it against bounds.
     let first_needle = needle[0];
+    let first_lower = first_needle.to_ascii_lowercase();
+    let first_upper = first_needle.to_ascii_uppercase();
+    // Only enable the ASCII fast-path if the needle itself is ASCII.
+    // If the needle is non-ASCII (e.g. Kelvin sign \u{212A}), it might still case-fold
+    // to an ASCII character, so we must fall back to full Unicode matching.
+    let can_fast_path = first_needle.is_ascii();
     let mut index = 0;
     while index + needle.len() <= haystack.len() {
         // Fast-path: short-circuit the full substring check if the first character
         // doesn't match, avoiding iterator overhead in the common case.
-        if !chars_eq_ignore_case(haystack[index], first_needle) {
+        let h = haystack[index];
+        if can_fast_path && h.is_ascii() && h != first_lower && h != first_upper {
+            index += 1;
+            continue;
+        }
+        if !chars_eq_ignore_case(h, first_needle) {
             index += 1;
             continue;
         }

patch.py

@@ -0,0 +1,43 @@
+import sys
+
+with open("crates/forktty-ui-gtk/src/gtk_app/terminal_search.rs", "r") as f:
+    text = f.read()
+
+search = """
+    let first_needle = needle[0];
+    let first_lower = first_needle.to_ascii_lowercase();
+    let first_upper = first_needle.to_ascii_uppercase();
+    let mut index = 0;
+    while index + needle.len() <= haystack.len() {
+        // Fast-path: short-circuit the full substring check if the first character
+        // doesn't match, avoiding iterator overhead in the common case.
+        let h = haystack[index];
+        if h.is_ascii() && h != first_lower && h != first_upper {
+            index += 1;
+            continue;
+        }
+"""
+
+replace = r"""
+    let first_needle = needle[0];
+    let first_lower = first_needle.to_ascii_lowercase();
+    let first_upper = first_needle.to_ascii_uppercase();
+    // Only enable the ASCII fast-path if the needle itself is ASCII.
+    // If the needle is non-ASCII (e.g. Kelvin sign \u{212A}), it might still case-fold
+    // to an ASCII character, so we must fall back to full Unicode matching.
+    let can_fast_path = first_needle.is_ascii();
+    let mut index = 0;
+    while index + needle.len() <= haystack.len() {
+        // Fast-path: short-circuit the full substring check if the first character
+        // doesn't match, avoiding iterator overhead in the common case.
+        let h = haystack[index];
+        if can_fast_path && h.is_ascii() && h != first_lower && h != first_upper {
+            index += 1;
+            continue;
+        }
+"""
+
+text = text.replace(search.strip(), replace.strip())
+
+with open("crates/forktty-ui-gtk/src/gtk_app/terminal_search.rs", "w") as f:
+    f.write(text)