📝 Add note about time.perf_counter() in middlewares (fastapi#12095)

docs/en/docs/tutorial/middleware.md

@@ -63,6 +63,12 @@ For example, you could add a custom header `X-Process-Time` containing the time
 {!../../../docs_src/middleware/tutorial001.py!}
 ```
 
+/// tip
+
+Here we use <a href="https://docs.python.org/3/library/time.html#time.perf_counter" class="external-link" target="_blank">`time.perf_counter()`</a> instead of `time.time()` because it can be more precise for these use cases. 🤓
+
+///
+
 ## Other middlewares
 
 You can later read more about other middlewares in the [Advanced User Guide: Advanced Middleware](../advanced/middleware.md){.internal-link target=_blank}.