diff --git a/benchmark_autocomplete.ts b/benchmark_autocomplete.ts
new file mode 100644
index 0000000..c3c130a
--- /dev/null
+++ b/benchmark_autocomplete.ts
@@ -0,0 +1,71 @@
+import { SumEngine } from "./src/engine/index.js";
+import { SumEditor } from "./src/ui/editor.js";
+
+// Not easy to fully instantiate the EditorView in Node without mocked DOM.
+// We can just create a standalone benchmark for the two methods of extracting variables.
+
+import { Text } from "@codemirror/state";
+
+const varPattern = /^\s*([\p{L}_][\p{L}\d_]*)\s*=/u;
+
+function methodOld(doc: Text) {
+  const options = [];
+  const iter = doc.iterLines();
+  for (let next = iter.next(); !next.done; next = iter.next()) {
+    const line = next.value;
+    if (line.includes("=")) {
+      const m = varPattern.exec(line);
+      if (m) {
+        options.push({ label: m[1], type: "variable" });
+      }
+    }
+  }
+  return options;
+}
+
+function methodNew(results: any[]) {
+  const options = [];
+  for (let i = 0, len = results.length; i < len; i++) {
+    const assign = results[i].assign;
+    if (assign) {
+      options.push({ label: assign, type: "variable" });
+    }
+  }
+  return options;
+}
+
+const lines = [];
+const results = [];
+for (let i = 0; i < 100000; i++) {
+  if (i % 10 === 0) {
+    lines.push(`var_${i} = ${i}`);
+    results.push({ assign: `var_${i}` });
+  } else {
+    lines.push(`just some text ${i} without equals`);
+    results.push({});
+  }
+}
+const docText = lines.join('\n');
+const doc = Text.of(lines);
+
+console.log("Warming up...");
+for(let i=0; i<10; i++) {
+  methodOld(doc);
+  methodNew(results);
+}
+
+console.log("Benchmarking Old Method...");
+const startOld = performance.now();
+for(let i=0; i<100; i++) {
+  methodOld(doc);
+}
+const endOld = performance.now();
+console.log(`Old Method: ${(endOld - startOld).toFixed(2)} ms`);
+
+console.log("Benchmarking New Method...");
+const startNew = performance.now();
+for(let i=0; i<100; i++) {
+  methodNew(results);
+}
+const endNew = performance.now();
+console.log(`New Method: ${(endNew - startNew).toFixed(2)} ms`);
diff --git a/src/ui/editor.ts b/src/ui/editor.ts
index dea37c8..6156742 100644
--- a/src/ui/editor.ts
+++ b/src/ui/editor.ts
@@ -170,7 +170,6 @@ export class SumEditor {
     this.resultsEl = resultsEl;
 
     let engineOptions: { label: string; type: string; detail?: string }[] | null = null;
-    const varPattern = /^\s*([\p{L}_][\p{L}\d_]*)\s*=/u;
     const completionSource = (ctx: CompletionContext): CompletionResult | null => {
       const word = ctx.matchBefore(/[\p{L}_]+$/u);
       if (!word || (word.from === word.to && !ctx.explicit)) return null;
@@ -183,14 +182,10 @@ export class SumEditor {
       }));
       const options = [...engineOptions];
       // document variables
-      const iter = ctx.state.doc.iterLines();
-      for (let next = iter.next(); !next.done; next = iter.next()) {
-        const line = next.value;
-        if (line.includes("=")) {
-          const m = varPattern.exec(line);
-          if (m) {
-            options.push({ label: m[1], type: "variable" });
-          }
+      for (let i = 0, len = this.results.length; i < len; i++) {
+        const assign = this.results[i].assign;
+        if (assign) {
+          options.push({ label: assign, type: "variable" });
         }
       }
       return { from: word.from, options, validFor: /^[\p{L}_]*$/u };