diff --git a/tools/lsp/Cargo.toml b/tools/lsp/Cargo.toml
index 9c857efc..984265a5 100644
--- a/tools/lsp/Cargo.toml
+++ b/tools/lsp/Cargo.toml
@@ -27,3 +27,7 @@ criterion = "0.8.2"
 [[bench]]
 name = "bench"
 harness = false
+
+[[bench]]
+name = "bench_diagnostic"
+harness = false
diff --git a/tools/lsp/benches/bench_diagnostic.rs b/tools/lsp/benches/bench_diagnostic.rs
new file mode 100644
index 00000000..b46a782d
--- /dev/null
+++ b/tools/lsp/benches/bench_diagnostic.rs
@@ -0,0 +1,17 @@
+use criterion::{criterion_group, criterion_main, Criterion};
+
+fn criterion_benchmark(c: &mut Criterion) {
+    let s = String::from("warning");
+    let target = "warning";
+
+    c.bench_function("contains", |b| {
+        b.iter(|| std::hint::black_box(&s).contains(std::hint::black_box(target)))
+    });
+
+    c.bench_function("eq", |b| {
+        b.iter(|| std::hint::black_box(&s) == std::hint::black_box(target))
+    });
+}
+
+criterion_group!(benches, criterion_benchmark);
+criterion_main!(benches);
diff --git a/tools/lsp/src/lib.rs b/tools/lsp/src/lib.rs
index 9e8845d5..7c3d18c5 100644
--- a/tools/lsp/src/lib.rs
+++ b/tools/lsp/src/lib.rs
@@ -1431,7 +1431,7 @@ impl LanguageServer for Backend {
         for diagnostic in params.context.diagnostics {
             if let Some(ref code) = diagnostic.code {
                 if let NumberOrString::String(ref s) = code {
-                    if s.contains("warning") {
+                    if s == "warning" {
                         let mut const_edits = Vec::new();
                         const_edits.push(TextEdit {
                             range: diagnostic.range,