Improve performance for noncallable attributes

[Krukov]

Description

The issue that this MR trying to fix, was described in the other MR that was not finished #8318
I faced the same problem, python spend most of the time in larges serializers with a lot of nested objects in is_simple_callable.
Based on your comments in mentioned MR, this MR contains only a 2 lines of code to fix this issue.
Here an example of code ( this issue effect almost all fields types):

from timeit import timeit
from rest_framework import serializers


class Comment:
    def __init__(self, email, number=0):
        self.email = email
        self.number = number


class CommentSerializer(serializers.Serializer):
    email = serializers.CharField()
    number = serializers.IntegerField()


comments = [Comment(email='[email protected]') for _ in range(100)]


def serialize():
    serializer = CommentSerializer(comments, many=True)
    return serializer.data


print(timeit('serialize()', number=1000, setup="from __main__ import serialize"))

This MR gives only 1-2% boost for 1 field object serialization, but about 50% boost for large and branched objects with a lot of fields

[tomchristie]

Okay, yup. Thanks!

[Krukov]

Thanks @tomchristie

Is it any chance that you will release it soon? I mean maybe you can tell how long it will take?