Avoid kwargs unpacking in _process_event hot path

CHANGELOG.md

@@ -15,6 +15,12 @@ You can find our backwards-compatibility policy [here](https://github.com/hynek/
 
 ## [Unreleased](https://github.com/hynek/structlog/compare/26.1.0...HEAD)
 
+### Changed
+
+- Logging is now slightly faster: `structlog.BoundLoggerBase._process_event` -- which runs on every log call -- no longer unpacks the event keyword arguments into a fresh keyword dict just to merge them into the event dict.
+  Passing the mapping positionally to `dict.update` is behavior-preserving and avoids that per-call overhead.
+  [#821](https://github.com/hynek/structlog/pull/821)
+
 
 ## [26.1.0](https://github.com/hynek/structlog/compare/25.5.0...26.1.0) - 2026-06-06
 

src/structlog/_base.py

@@ -166,7 +166,7 @@ def _process_event(
         # We're typing it as Any, because processors can return more than an
         # EventDict.
         event_dict: Any = self._context.copy()
-        event_dict.update(**event_kw)
+        event_dict.update(event_kw)
 
         if event is not None:
             event_dict["event"] = event