gh-103193: Speedup and inline inspect._is_type

[AlexWaygood]

(Using @sobolevn's benchmark script from #103193 (comment).)

Benchmarks on main:

type[Foo]                :   74 ±  0 ns
Foo                      :  177 ±  1 ns
type[Bar]                :   74 ±  0 ns
Bar                      :  177 ±  0 ns
WithParentClassX         :  229 ±  0 ns
Baz                      :  216 ±  0 ns
WithParentX              :  266 ±  1 ns
type[Missing]            :  210 ±  0 ns
Missing                  :  219 ±  1 ns
Slotted                  :  214 ±  0 ns
Method                   :  178 ±  0 ns
StMethod                 :  178 ±  0 ns
ClsMethod                :  178 ±  1 ns

Benchmarks with this PR:

type[Foo]                :   74 ±  0 ns
Foo                      :  134 ±  0 ns
type[Bar]                :   74 ±  0 ns
Bar                      :  133 ±  0 ns
WithParentClassX         :  187 ±  0 ns
Baz                      :  171 ±  0 ns
WithParentX              :  220 ±  0 ns
type[Missing]            :  210 ±  1 ns
Missing                  :  174 ±  0 ns
Slotted                  :  169 ±  0 ns
Method                   :  133 ±  0 ns
StMethod                 :  133 ±  0 ns
ClsMethod                :  133 ±  0 ns

This speeds up this isinstance() call 1.25x relative to main:

from typing import *

@runtime_checkable
class Foo(Protocol):
    a: int
    b: int
    c: int
    d: int
    e: int
    f: int
    g: int
    h: int
    i: int
    j: int

class Bar:
    def __init__(self):
        for attrname in 'abcdefghij':
            setattr(self, attrname, 42)

isinstance(Bar(), Foo)

• Issue: Optimise inspect.getattr_static #103193

[carljm]

The improvements keep on coming!

[carljm]

This has equivalent semantics with less code and fewer assignments, but perhaps it muddies the semantics of the klass var a bit (since it will temporarily be "wrong" in the case that obj is already a type.) No strong feelings, whatever you prefer.

Suggested change

	objtype = type(obj)
	if type not in _static_getmro(objtype):
	klass = objtype
	klass = type(obj)
	if type not in _static_getmro(klass):

[AlexWaygood]

Hmm. Yeah, I see what you mean, but I think I'd prefer to keep the semantics of klass clear here :)

[AlexWaygood]

The improvements keep on coming!

Optimisations will continue until morale improves!