diff --git a/packages/adapters/python/src/usage/imports.ts b/packages/adapters/python/src/usage/imports.ts
index 6079306f..65b7d1b8 100644
--- a/packages/adapters/python/src/usage/imports.ts
+++ b/packages/adapters/python/src/usage/imports.ts
@@ -388,9 +388,26 @@ function importlibAliases(
     for (let s = scope; s >= 0; s = parent[s]!) if (s === of) return true;
     return false;
   };
+  // Identifier -> statements that mention it. A statement can only rebind a
+  // name it contains, so each alias checks just those statements instead of
+  // rescanning the whole file once per alias (quadratic on many aliases).
+  const mentions = new Map<string, number[]>();
+  const identifier = /[\p{XID_Start}_][\p{XID_Continue}]*/gu;
+  texts.forEach((raw, index) => {
+    const seenHere = new Set<string>();
+    for (const form of new Set([raw, raw.normalize("NFKC")])) {
+      for (const m of form.matchAll(identifier)) seenHere.add(m[0]);
+    }
+    for (const word of seenHere) {
+      const list = mentions.get(word);
+      if (list) list.push(index);
+      else mentions.set(word, [index]);
+    }
+  });
   for (const [scope, names] of bound) {
     for (const name of [...names.keys()]) {
-      const dropped = texts.some((raw, index) => {
+      const dropped = (mentions.get(name) ?? []).some((index) => {
+        const raw = texts[index]!;
         if (!inside(scopeOf[index]!, scope)) return false;
         const own = defs.get(index)?.filter((d) => d.name === name) ?? [];
         const parsed = statementParts(raw);
diff --git a/packages/adapters/python/src/usage/usage.test.ts b/packages/adapters/python/src/usage/usage.test.ts
index a76ca59a..680e4afb 100644
--- a/packages/adapters/python/src/usage/usage.test.ts
+++ b/packages/adapters/python/src/usage/usage.test.ts
@@ -124,6 +124,23 @@ describe("extractPythonImports", () => {
     );
   });
 
+  it("scans many importlib aliases in linear time", () => {
+    const count = 1000;
+    const source =
+      Array.from({ length: count }, (_, i) => `import importlib as il${i}`).join("\n") +
+      '\nil0.import_module("yaml")\nil999.import_module("toml")\n' +
+      'il5 = other\nil5.import_module("dropped")\n';
+    const started = performance.now();
+    const dynamic = extractPythonImports(source)
+      .imports.filter((i) => i.form === "dynamic")
+      .map((i) => i.module);
+    const elapsed = performance.now() - started;
+    // Correctness first: a rebound alias is still dropped, the others credited.
+    assert.deepEqual(dynamic, ["yaml", "toml"]);
+    // 1000 aliases took ~5s when every alias rescanned every statement.
+    assert.ok(elapsed < 1500, `took ${Math.round(elapsed)}ms`);
+  });
+
   it("credits aliased importlib, import_module and __import__ calls", () => {
     const dyn = (src: string) =>
       extractPythonImports(src)