From 2c0c48155d89e6174ba966b052f7aca4f813a52f Mon Sep 17 00:00:00 2001
From: Mike Hsu <mike.hsu@gmail.com>
Date: Sat, 9 Mar 2024 22:15:44 -0800
Subject: [PATCH] add a perf note

---
 crates/bevy_ecs/src/query/state.rs | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/crates/bevy_ecs/src/query/state.rs b/crates/bevy_ecs/src/query/state.rs
index 4e6e388787f40..71eda8c14a864 100644
--- a/crates/bevy_ecs/src/query/state.rs
+++ b/crates/bevy_ecs/src/query/state.rs
@@ -411,6 +411,12 @@ impl<D: QueryData, F: QueryFilter> QueryState<D, F> {
     /// safe methods on `QueryState` call [`QueryState::update_archetypes`] internally, so
     /// this is best used through a `Query`.
     ///
+    /// ## Performance
+    ///
+    /// This will have similar performance as constructing a new `QueryState` since much of internal state
+    /// needs to be reconstructed. But it will be a little faster as it only needs to compare the intersection
+    /// of matching archetypes rather than iterating over all archetypes.
+    ///
     /// ## Panics
     ///
     /// Will panic if `NewD` contains accesses not in `Q` or `OtherQ`.