diff --git a/src/repo_context.rs b/src/repo_context.rs
index 02d99c0..2dce47c 100644
--- a/src/repo_context.rs
+++ b/src/repo_context.rs
@@ -936,17 +936,20 @@ impl RepoContextExtractor {
         file_content: &str,
         keywords: &[String],
     ) -> Vec<FileContentMatch> {
-        let lines: Vec<String> = file_content.lines().map(|s| s.to_string()).collect();
+        let lines: Vec<&str> = file_content.lines().collect();
         if lines.is_empty() {
             return Vec::new();
         }
 
+        // Pre-calculate lowercased keywords to avoid repeated allocation
+        let keywords_lower: Vec<String> = keywords.iter().map(|k| k.to_lowercase()).collect();
+
         // Find line numbers that contain any of the keywords (case-insensitive)
         let mut matching_lines = HashSet::new();
         for (line_idx, line) in lines.iter().enumerate() {
             let line_lower = line.to_lowercase();
-            for keyword in keywords {
-                if line_lower.contains(&keyword.to_lowercase()) {
+            for keyword in &keywords_lower {
+                if line_lower.contains(keyword) {
                     matching_lines.insert(line_idx);
                     break; // Found a match, no need to check other keywords for this line
                 }
@@ -985,7 +988,8 @@ impl RepoContextExtractor {
         // Convert ranges to FileContentMatch structs
         let mut matches = Vec::new();
         for (start, end) in merged_ranges {
-            let range_lines = lines[start..=end].to_vec();
+            let range_lines: Vec<String> =
+                lines[start..=end].iter().map(|&s| s.to_string()).collect();
             matches.push(FileContentMatch {
                 start_line: start + 1, // Convert to 1-based line numbering
                 end_line: end + 1,     // Convert to 1-based line numbering
diff --git a/src/tests/mod.rs b/src/tests/mod.rs
index 53cd5d5..0b66f88 100644
--- a/src/tests/mod.rs
+++ b/src/tests/mod.rs
@@ -28,4 +28,6 @@ pub mod polling_test;
 #[cfg(test)]
 pub mod polling_tests;
 #[cfg(test)]
+pub mod repo_context_perf_test;
+#[cfg(test)]
 pub mod repo_context_tests;
diff --git a/src/tests/repo_context_perf_test.rs b/src/tests/repo_context_perf_test.rs
new file mode 100644
index 0000000..93a5e6f
--- /dev/null
+++ b/src/tests/repo_context_perf_test.rs
@@ -0,0 +1,64 @@
+#[cfg(test)]
+mod tests {
+    use crate::config::AppSettings;
+    use crate::file_indexer::FileIndexManager;
+    use crate::gitlab::GitlabApiClient;
+    use crate::repo_context::RepoContextExtractor;
+    use std::sync::Arc;
+    use std::time::Instant;
+
+    #[test]
+    fn test_extract_relevant_file_sections_perf() {
+        // Setup minimal extractor
+        let settings = AppSettings {
+            context_lines: 5,
+            ..Default::default()
+        };
+        let settings_arc = Arc::new(settings);
+        // We use a dummy client since we won't be making network calls,
+        // but we need to construct it properly to satisfy types.
+        let mut minimal_settings = AppSettings::default();
+        minimal_settings.gitlab_url = "https://example.com".to_string();
+        minimal_settings.gitlab_token = "dummy".to_string();
+        minimal_settings.openai_api_key = "dummy".to_string();
+
+        let valid_settings = Arc::new(minimal_settings);
+        let gitlab_client = Arc::new(GitlabApiClient::new(valid_settings.clone()).unwrap());
+        let file_index_manager = Arc::new(FileIndexManager::new(gitlab_client.clone(), 3600));
+
+        let extractor = RepoContextExtractor::new_with_file_indexer(
+            gitlab_client,
+            settings_arc, // This one is used for context_lines
+            file_index_manager,
+        );
+
+        // Generate large content
+        // 100,000 lines, ~50 chars per line -> ~5MB
+        let line_count = 100_000;
+        let mut content = String::with_capacity(line_count * 60);
+        for i in 0..line_count {
+            if i % 1000 == 0 {
+                content.push_str("This line contains the magic keyword TARGET.\n");
+            } else {
+                content.push_str(
+                    "This is a regular line of code with some content that is not relevant.\n",
+                );
+            }
+        }
+
+        let keywords = vec!["TARGET".to_string()];
+
+        println!("Starting benchmark with {} lines...", line_count);
+        let start = Instant::now();
+
+        // Run multiple times to average? Or just once for large enough dataset.
+        // 100k lines should be enough to see difference.
+        let _matches = extractor.extract_relevant_file_sections(&content, &keywords);
+
+        let duration = start.elapsed();
+        println!("Extraction took: {:?}", duration);
+
+        // Sanity check
+        assert!(!_matches.is_empty());
+    }
+}