From 0ce955063f363a2eae888a5c561f07d70cee5593 Mon Sep 17 00:00:00 2001
From: JK <19386515+Johnny-Kao@users.noreply.github.com>
Date: Fri, 2 Oct 2026 03:15:46 +0900
Subject: [PATCH 1/2] Improve astuple nested atomic sequence performance

---
 bench/test_benchmarks.py | 16 ++++++++++++++++
 src/attr/_funcs.py       |  2 +-
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/bench/test_benchmarks.py b/bench/test_benchmarks.py
index 6adf21aa5..c71303306 100644
--- a/bench/test_benchmarks.py
+++ b/bench/test_benchmarks.py
@@ -177,6 +177,22 @@ def test_astuple_atomic():
         at(c)
 
 
+@attrs.define
+class NestedAtomicFields:
+    sequence: list[int] = attrs.Factory(lambda: list(range(100)))
+
+
+def test_astuple_nested_atomic():
+    """
+    Benchmark atomic values nested in a sequence.
+    """
+    c = NestedAtomicFields()
+    at = attrs.astuple
+
+    for _ in range(ROUNDS):
+        at(c)
+
+
 class TestCachedProperties:
     @attrs.define
     class Slotted:
diff --git a/src/attr/_funcs.py b/src/attr/_funcs.py
index d213efc22..c88c175a1 100644
--- a/src/attr/_funcs.py
+++ b/src/attr/_funcs.py
@@ -301,7 +301,7 @@ def astuple(
                             tuple_factory=tuple_factory,
                             retain_collection_types=retain,
                         )
-                        if has(j.__class__)
+                        if type(j) not in _ATOMIC_TYPES and has(j.__class__)
                         else j
                     )
                     for j in v

From 0c504ac0426ec40d56d0e0de11eea5cee26c61f9 Mon Sep 17 00:00:00 2001
From: JK <19386515+Johnny-Kao@users.noreply.github.com>
Date: Fri, 2 Oct 2026 03:17:18 +0900
Subject: [PATCH 2/2] Add changelog for astuple sequence optimization

---
 changelog.d/1636.change.md | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 changelog.d/1636.change.md

diff --git a/changelog.d/1636.change.md b/changelog.d/1636.change.md
new file mode 100644
index 000000000..f41d63260
--- /dev/null
+++ b/changelog.d/1636.change.md
@@ -0,0 +1 @@
+Improved `attrs.astuple()` performance for atomic values nested in sequences by avoiding unnecessary attrs-class detection.