Cache requires-python checks & skip debug logging

news/13128.feature.rst

@@ -0,0 +1 @@
+Cache ``python-requires`` checks while filtering potential installation candidates.

src/pip/_internal/index/package_finder.py

@@ -732,6 +732,11 @@ def _sort_links(self, links: Iterable[Link]) -> List[Link]:
         return no_eggs + eggs
 
     def _log_skipped_link(self, link: Link, result: LinkType, detail: str) -> None:
+        # This is a hot method so don't waste time hashing links unless we're
+        # actually going to log 'em.
+        if not logger.isEnabledFor(logging.DEBUG):
+            return
+
         entry = (link, result, detail)
         if entry not in self._logged_links:
             # Put the link at the end so the reason is more visible and because

src/pip/_internal/utils/packaging.py

@@ -11,6 +11,7 @@
 logger = logging.getLogger(__name__)
 
 
+@functools.lru_cache(maxsize=96)
 def check_requires_python(
     requires_python: Optional[str], version_info: Tuple[int, ...]
 ) -> bool: