ClassBuilder: eval only once (#1407)

* ClassBuilder: eval only once

* avoid Attribute.evolve

* speed up `_make_attr_tuple_class`

* speed up `_add_method_dunders`

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* optimize _CountingAttrs more

* Fix up `_add_method_dunders`

* avoid a hot splitlines

* restore old type_hash

* fix scriptlines handling

* restore contextlib.suppress

* Revert "fix scriptlines handling"

This reverts commit 4e0af4b.

* Revert "avoid a hot splitlines"

This reverts commit 532faed.

* add some hints

* fix tests

* Refactor `_Attributes`

* Reflow

* Reflow docs

* Microoptimization

* Rework type hints a little

* Fix arg name

* Add changelog entry

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: Tinche

changelog.d/1407.change.md

@@ -0,0 +1 @@
+Speed up class creation by 30%-50% by compiling methods only once and using a variety of other techniques.

src/attr/_cmp.py

@@ -4,7 +4,7 @@
 import functools
 import types
 
-from ._make import _make_ne
+from ._make import __ne__
 
 
 _operation_names = {"eq": "==", "lt": "<", "le": "<=", "gt": ">", "ge": ">="}
@@ -71,7 +71,7 @@ def cmp_using(
     if eq is not None:
         has_eq_function = True
         body["__eq__"] = _make_operator("eq", eq)
-        body["__ne__"] = _make_ne()
+        body["__ne__"] = __ne__
 
     if lt is not None:
         num_order_functions += 1