PYTHON-4455 Improve import time on Windows (#1645)

Author: blink1073

doc/changelog.rst

@@ -4,6 +4,8 @@ Changelog
 Changes in Version 4.8.0
 -------------------------
 
+The handshake metadata for "os.name" on Windows has been simplified to "Windows" to improve import time.
+
 .. warning:: PyMongo 4.8 drops support for Python 3.7 and PyPy 3.8: Python 3.8+ or PyPy 3.9+ is now required.
 
 Changes in Version 4.7.2

pymongo/pool.py

@@ -211,13 +211,14 @@ def _set_keepalive_times(sock: socket.socket) -> None:
         "version": platform.mac_ver()[0],
     }
 elif sys.platform == "win32":
+    _ver = sys.getwindowsversion()
     _METADATA["os"] = {
-        "type": platform.system(),
-        # "Windows XP", "Windows 7", "Windows 10", etc.
-        "name": " ".join((platform.system(), platform.release())),
-        "architecture": platform.machine(),
-        # Windows patch level (e.g. 5.1.2600-SP3)
-        "version": "-".join(platform.win32_ver()[1:3]),
+        "type": "Windows",
+        "name": "Windows",
+        # Avoid using platform calls, see PYTHON-4455.
+        "architecture": os.environ.get("PROCESSOR_ARCHITECTURE") or platform.machine(),
+        # Windows patch level (e.g. 10.0.17763-SP0).
+        "version": ".".join(map(str, _ver[:3])) + f"-SP{_ver[-1] or '0'}",
     }
 elif sys.platform.startswith("java"):
     _name, _ver, _arch = platform.java_ver()[-1]