[PR #7819/dfc3f899 backport][3.9] Skip filtering CookieJar when t…

…he jar is empty or all cookies have expired (#7822)

**This is a backport of PR #7819 as merged into master (dfc3f89).**

<!-- Thank you for your contribution! -->

## What do these changes do?

The filtering itself and its preparation in `CookieJar.filter_cookies()`
is expensive. Sometimes there are no cookies in the jar or all cookies
have expired. Skip filtering and its preparation in this case.

Because the empty check is much cheaper than `_do_expiration()`, I think
it deserves to be duplicated before and after calling
`_do_expiration()`.

```console
$ python3.11 -m timeit -s 'from collections import defaultdict; d=defaultdict(foo="bar")' \
> 'if not d: pass'
50000000 loops, best of 5: 8.3 nsec per loop
$ python3.11 -m timeit -s 'from collections import defaultdict; d=defaultdict()' \
> 'if not d: pass'
50000000 loops, best of 5: 8.74 nsec per loop
$ python3.11 -m timeit -s 'from aiohttp import CookieJar; cj = CookieJar()' \
> 'cj._do_expiration()'
200000 loops, best of 5: 1.86 usec per loop
```

<!-- Please give a short brief about these changes. -->

## Are there changes in behavior for the user?

No.

<!-- Outline any notable behaviour for the end users. -->

## Related issue number

#7583 (comment)

<!-- Are there any issues opened that will be resolved by merging this
change? -->

## Checklist

- [x] I think the code is well written
- [ ] Unit tests for the changes exist
- [ ] Documentation reflects the changes
- [x] If you provide code modification, please add yourself to
`CONTRIBUTORS.txt`
  * The format is &lt;Name&gt; &lt;Surname&gt;.
  * Please keep alphabetical order, the file is sorted by names.
- [x] Add a new news fragment into the `CHANGES` folder
  * name it `<issue_id>.<type>` for example (588.bugfix)
* if you don't have an `issue_id` change it to the pr id after creating
the pr
  * ensure type is one of the following:
    * `.feature`: Signifying a new feature.
    * `.bugfix`: Signifying a bug fix.
    * `.doc`: Signifying a documentation improvement.
    * `.removal`: Signifying a deprecation or removal of public API.
* `.misc`: A ticket has been closed, but it is not of interest to users.
* Make sure to use full sentences with correct case and punctuation, for
example: "Fix issue with non-ascii contents in doctest text files."

CHANGES/7819.feature

@@ -0,0 +1 @@
+Skip filtering ``CookieJar`` when the jar is empty or all cookies have expired.

CONTRIBUTORS.txt

@@ -273,6 +273,7 @@ Required Field
 Robert Lu
 Robert Nikolich
 Roman Podoliaka
+Rong Zhang
 Samir Akarioh
 Samuel Colvin
 Sean Hunt

aiohttp/cookiejar.py

@@ -236,11 +236,17 @@ def filter_cookies(
         self, request_url: URL = URL()
     ) -> Union["BaseCookie[str]", "SimpleCookie[str]"]:
         """Returns this jar's cookies filtered by their attributes."""
-        self._do_expiration()
-        request_url = URL(request_url)
         filtered: Union["SimpleCookie[str]", "BaseCookie[str]"] = (
             SimpleCookie() if self._quote_cookie else BaseCookie()
         )
+        if not self._cookies:
+            # Skip do_expiration() if there are no cookies.
+            return filtered
+        self._do_expiration()
+        if not self._cookies:
+            # Skip rest of function if no non-expired cookies.
+            return filtered
+        request_url = URL(request_url)
         hostname = request_url.raw_host or ""
         request_origin = URL()
         with contextlib.suppress(ValueError):