Improve performance of startswith, endswith, count, *find, and *index methods for str, bytes and bytearray

Feature or enhancement

Proposal:

We can improve performance of str.startswith and other methods for the single-argument case by creating a fast path in the single argument parsing.

Has this already been discussed elsewhere?

This is a minor feature, which does not need previous discussion elsewhere

Links to previous discussion of this feature:

https://github.com/faster-cpython/ideas/issues/671

Linked PRs

• gh-117432
• gh-117466
• gh-117468
• gh-117480
• gh-117495
• gh-117499
• gh-117502
• gh-117590
• gh-117591
• gh-117782

先查看提案和链接的 PR（gh-117432、gh-117466、gh-117468、gh-117480、gh-117495、gh-117499、gh-117502、gh-117590、gh-117591 和 gh-117782），以了解当前实现并避免重复工作。当列出的 str、bytes 和 bytearray 方法的单参数路径显示出预期的性能提升时，即表示完成。