From a774329534e52ca9a003f75ce083b8871947d590 Mon Sep 17 00:00:00 2001
From: Alex Saveau <saveau.alexandre@gmail.com>
Date: Tue, 25 Jan 2022 13:04:34 -0800
Subject: [PATCH 01/14] Slight perf improvements and tidy for bevymark

Signed-off-by: Alex Saveau <saveau.alexandre@gmail.com>
---
 examples/tools/bevymark.rs | 123 +++++++++++++++++++++----------------
 1 file changed, 69 insertions(+), 54 deletions(-)

diff --git a/examples/tools/bevymark.rs b/examples/tools/bevymark.rs
index 290fdf42594aa..60985b0f5d5eb 100644
--- a/examples/tools/bevymark.rs
+++ b/examples/tools/bevymark.rs
@@ -1,9 +1,12 @@
+use std::fmt::Write;
+
+use rand::{thread_rng, Rng};
+
 use bevy::{
     core::FixedTimestep,
     diagnostic::{Diagnostics, FrameTimeDiagnosticsPlugin, LogDiagnosticsPlugin},
     prelude::*,
 };
-use rand::random;
 
 const BIRDS_PER_SECOND: u32 = 10000;
 const _BASE_COLOR: Color = Color::rgb(5.0, 5.0, 5.0);
@@ -72,67 +75,74 @@ fn scheduled_spawner(
             scheduled.per_wave,
             bird_texture.0.clone_weak(),
         );
-        counter.color = Color::rgb_linear(random(), random(), random());
+
+        let mut random = thread_rng();
+        counter.color = Color::rgb_linear(random.gen(), random.gen(), random.gen());
         scheduled.wave -= 1;
     }
 }
 
 struct BirdTexture(Handle<Image>);
 
+#[derive(Component)]
+struct StatsText;
+
 fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
     let texture = asset_server.load("branding/icon.png");
 
     commands.spawn_bundle(OrthographicCameraBundle::new_2d());
     commands.spawn_bundle(UiCameraBundle::default());
-    commands.spawn_bundle(TextBundle {
-        text: Text {
-            sections: vec![
-                TextSection {
-                    value: "Bird Count: ".to_string(),
-                    style: TextStyle {
-                        font: asset_server.load("fonts/FiraSans-Bold.ttf"),
-                        font_size: 40.0,
-                        color: Color::rgb(0.0, 1.0, 0.0),
+    commands
+        .spawn_bundle(TextBundle {
+            text: Text {
+                sections: vec![
+                    TextSection {
+                        value: "Bird Count: ".to_string(),
+                        style: TextStyle {
+                            font: asset_server.load("fonts/FiraSans-Bold.ttf"),
+                            font_size: 40.0,
+                            color: Color::rgb(0.0, 1.0, 0.0),
+                        },
                     },
-                },
-                TextSection {
-                    value: "".to_string(),
-                    style: TextStyle {
-                        font: asset_server.load("fonts/FiraSans-Bold.ttf"),
-                        font_size: 40.0,
-                        color: Color::rgb(0.0, 1.0, 1.0),
+                    TextSection {
+                        value: "".to_string(),
+                        style: TextStyle {
+                            font: asset_server.load("fonts/FiraSans-Bold.ttf"),
+                            font_size: 40.0,
+                            color: Color::rgb(0.0, 1.0, 1.0),
+                        },
                     },
-                },
-                TextSection {
-                    value: "\nAverage FPS: ".to_string(),
-                    style: TextStyle {
-                        font: asset_server.load("fonts/FiraSans-Bold.ttf"),
-                        font_size: 40.0,
-                        color: Color::rgb(0.0, 1.0, 0.0),
+                    TextSection {
+                        value: "\nAverage FPS: ".to_string(),
+                        style: TextStyle {
+                            font: asset_server.load("fonts/FiraSans-Bold.ttf"),
+                            font_size: 40.0,
+                            color: Color::rgb(0.0, 1.0, 0.0),
+                        },
                     },
-                },
-                TextSection {
-                    value: "".to_string(),
-                    style: TextStyle {
-                        font: asset_server.load("fonts/FiraSans-Bold.ttf"),
-                        font_size: 40.0,
-                        color: Color::rgb(0.0, 1.0, 1.0),
+                    TextSection {
+                        value: "".to_string(),
+                        style: TextStyle {
+                            font: asset_server.load("fonts/FiraSans-Bold.ttf"),
+                            font_size: 40.0,
+                            color: Color::rgb(0.0, 1.0, 1.0),
+                        },
                     },
+                ],
+                ..Default::default()
+            },
+            style: Style {
+                position_type: PositionType::Absolute,
+                position: Rect {
+                    top: Val::Px(5.0),
+                    left: Val::Px(5.0),
+                    ..Default::default()
                 },
-            ],
-            ..Default::default()
-        },
-        style: Style {
-            position_type: PositionType::Absolute,
-            position: Rect {
-                top: Val::Px(5.0),
-                left: Val::Px(5.0),
                 ..Default::default()
             },
             ..Default::default()
-        },
-        ..Default::default()
-    });
+        })
+        .insert(StatsText);
 
     commands.insert_resource(BirdTexture(texture));
     commands.insert_resource(BirdScheduled {
@@ -156,7 +166,8 @@ fn mouse_handler(
     mut counter: ResMut<BevyCounter>,
 ) {
     if mouse_button_input.just_released(MouseButton::Left) {
-        counter.color = Color::rgb_linear(random(), random(), random());
+        let mut random = thread_rng();
+        counter.color = Color::rgb_linear(random.gen(), random.gen(), random.gen());
     }
 
     if mouse_button_input.pressed(MouseButton::Left) {
@@ -181,6 +192,8 @@ fn spawn_birds(
     let window = windows.get_primary().unwrap();
     let bird_x = (window.width() as f32 / -2.) + HALF_BIRD_SIZE;
     let bird_y = (window.height() as f32 / 2.) - HALF_BIRD_SIZE;
+    let mut random = thread_rng();
+
     for count in 0..spawn_count {
         let bird_z = (counter.count + count) as f32 * 0.00001;
         commands
@@ -199,7 +212,7 @@ fn spawn_birds(
             })
             .insert(Bird {
                 velocity: Vec3::new(
-                    rand::random::<f32>() * MAX_VELOCITY - (MAX_VELOCITY * 0.5),
+                    random.gen::<f32>() * MAX_VELOCITY - (MAX_VELOCITY * 0.5),
                     0.,
                     0.,
                 ),
@@ -209,11 +222,11 @@ fn spawn_birds(
 }
 
 fn movement_system(time: Res<Time>, mut bird_query: Query<(&mut Bird, &mut Transform)>) {
-    for (mut bird, mut transform) in bird_query.iter_mut() {
+    bird_query.for_each_mut(|(mut bird, mut transform)| {
         transform.translation.x += bird.velocity.x * time.delta_seconds();
         transform.translation.y += bird.velocity.y * time.delta_seconds();
         bird.velocity.y += GRAVITY * time.delta_seconds();
-    }
+    });
 }
 
 fn collision_system(windows: Res<Windows>, mut bird_query: Query<(&mut Bird, &Transform)>) {
@@ -221,7 +234,7 @@ fn collision_system(windows: Res<Windows>, mut bird_query: Query<(&mut Bird, &Tr
     let half_width = window.width() as f32 * 0.5;
     let half_height = window.height() as f32 * 0.5;
 
-    for (mut bird, transform) in bird_query.iter_mut() {
+    bird_query.for_each_mut(|(mut bird, transform)| {
         let x_vel = bird.velocity.x;
         let y_vel = bird.velocity.y;
         let x_pos = transform.translation.x;
@@ -238,20 +251,22 @@ fn collision_system(windows: Res<Windows>, mut bird_query: Query<(&mut Bird, &Tr
         if y_pos + HALF_BIRD_SIZE > half_height && y_vel > 0.0 {
             bird.velocity.y = 0.0;
         }
-    }
+    });
 }
 
 fn counter_system(
     diagnostics: Res<Diagnostics>,
     counter: Res<BevyCounter>,
-    mut query: Query<&mut Text>,
+    mut query: Query<&mut Text, With<StatsText>>,
 ) {
     if let Some(fps) = diagnostics.get(FrameTimeDiagnosticsPlugin::FPS) {
         if let Some(average) = fps.average() {
-            for mut text in query.iter_mut() {
-                text.sections[1].value = format!("{}", counter.count);
-                text.sections[3].value = format!("{:.2}", average);
-            }
+            let mut text = query.single_mut();
+
+            text.sections[1].value.clear();
+            write!(text.sections[1].value, "{}", counter.count).unwrap();
+            text.sections[3].value.clear();
+            write!(text.sections[3].value, "{:.2}", average).unwrap();
         }
     };
 }

From 0d2bebc8bf963862a79d568b7e1bb2dfb18e7959 Mon Sep 17 00:00:00 2001
From: Alex Saveau <saveau.alexandre@gmail.com>
Date: Tue, 25 Jan 2022 14:40:03 -0800
Subject: [PATCH 02/14] Rename random to rng

Signed-off-by: Alex Saveau <saveau.alexandre@gmail.com>
---
 examples/tools/bevymark.rs | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/examples/tools/bevymark.rs b/examples/tools/bevymark.rs
index 60985b0f5d5eb..11a122820c988 100644
--- a/examples/tools/bevymark.rs
+++ b/examples/tools/bevymark.rs
@@ -76,8 +76,8 @@ fn scheduled_spawner(
             bird_texture.0.clone_weak(),
         );
 
-        let mut random = thread_rng();
-        counter.color = Color::rgb_linear(random.gen(), random.gen(), random.gen());
+        let mut rng = thread_rng();
+        counter.color = Color::rgb_linear(rng.gen(), rng.gen(), rng.gen());
         scheduled.wave -= 1;
     }
 }
@@ -166,8 +166,8 @@ fn mouse_handler(
     mut counter: ResMut<BevyCounter>,
 ) {
     if mouse_button_input.just_released(MouseButton::Left) {
-        let mut random = thread_rng();
-        counter.color = Color::rgb_linear(random.gen(), random.gen(), random.gen());
+        let mut rng = thread_rng();
+        counter.color = Color::rgb_linear(rng.gen(), rng.gen(), rng.gen());
     }
 
     if mouse_button_input.pressed(MouseButton::Left) {
@@ -192,7 +192,7 @@ fn spawn_birds(
     let window = windows.get_primary().unwrap();
     let bird_x = (window.width() as f32 / -2.) + HALF_BIRD_SIZE;
     let bird_y = (window.height() as f32 / 2.) - HALF_BIRD_SIZE;
-    let mut random = thread_rng();
+    let mut rng = thread_rng();
 
     for count in 0..spawn_count {
         let bird_z = (counter.count + count) as f32 * 0.00001;
@@ -212,7 +212,7 @@ fn spawn_birds(
             })
             .insert(Bird {
                 velocity: Vec3::new(
-                    random.gen::<f32>() * MAX_VELOCITY - (MAX_VELOCITY * 0.5),
+                    rng.gen::<f32>() * MAX_VELOCITY - (MAX_VELOCITY * 0.5),
                     0.,
                     0.,
                 ),

From 6e6158c52705499ab3d9366e53beea0308b96a5e Mon Sep 17 00:00:00 2001
From: Alex Saveau <saveau.alexandre@gmail.com>
Date: Tue, 25 Jan 2022 15:18:44 -0800
Subject: [PATCH 03/14] Smush imports together

Signed-off-by: Alex Saveau <saveau.alexandre@gmail.com>
---
 examples/tools/bevymark.rs | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/examples/tools/bevymark.rs b/examples/tools/bevymark.rs
index 11a122820c988..beffc7d7b9e48 100644
--- a/examples/tools/bevymark.rs
+++ b/examples/tools/bevymark.rs
@@ -1,12 +1,10 @@
-use std::fmt::Write;
-
-use rand::{thread_rng, Rng};
-
 use bevy::{
     core::FixedTimestep,
     diagnostic::{Diagnostics, FrameTimeDiagnosticsPlugin, LogDiagnosticsPlugin},
     prelude::*,
 };
+use rand::{thread_rng, Rng};
+use std::fmt::Write;
 
 const BIRDS_PER_SECOND: u32 = 10000;
 const _BASE_COLOR: Color = Color::rgb(5.0, 5.0, 5.0);

From 16622b3e4e60598cc4fc6f3f938d2f876d0fd161 Mon Sep 17 00:00:00 2001
From: Alex Saveau <saveau.alexandre@gmail.com>
Date: Tue, 25 Jan 2022 16:03:35 -0800
Subject: [PATCH 04/14] Only update counter when changed

Signed-off-by: Alex Saveau <saveau.alexandre@gmail.com>
---
 examples/tools/bevymark.rs | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/examples/tools/bevymark.rs b/examples/tools/bevymark.rs
index beffc7d7b9e48..cb4ad4bbabbe7 100644
--- a/examples/tools/bevymark.rs
+++ b/examples/tools/bevymark.rs
@@ -257,12 +257,15 @@ fn counter_system(
     counter: Res<BevyCounter>,
     mut query: Query<&mut Text, With<StatsText>>,
 ) {
+    let mut text = query.single_mut();
+
+    if counter.is_changed() {
+        text.sections[1].value.clear();
+        write!(text.sections[1].value, "{}", counter.count).unwrap();
+    }
+
     if let Some(fps) = diagnostics.get(FrameTimeDiagnosticsPlugin::FPS) {
         if let Some(average) = fps.average() {
-            let mut text = query.single_mut();
-
-            text.sections[1].value.clear();
-            write!(text.sections[1].value, "{}", counter.count).unwrap();
             text.sections[3].value.clear();
             write!(text.sections[3].value, "{:.2}", average).unwrap();
         }

From d2f67e945ae3fcc19d46915bc772fee505c59c5b Mon Sep 17 00:00:00 2001
From: Alex Saveau <saveau.alexandre@gmail.com>
Date: Thu, 24 Feb 2022 14:53:57 -0800
Subject: [PATCH 05/14] Add note about for_each being faster

Signed-off-by: Alex Saveau <saveau.alexandre@gmail.com>
---
 examples/tools/bevymark.rs | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/examples/tools/bevymark.rs b/examples/tools/bevymark.rs
index cb4ad4bbabbe7..5fc8aaefcc91a 100644
--- a/examples/tools/bevymark.rs
+++ b/examples/tools/bevymark.rs
@@ -220,6 +220,8 @@ fn spawn_birds(
 }
 
 fn movement_system(time: Res<Time>, mut bird_query: Query<(&mut Bird, &mut Transform)>) {
+    // Use for_each style iteration here and in the collision_system because it's faster thanks to
+    // better LLVM optimization opportunities (see transrangers) and hoisted branching.
     bird_query.for_each_mut(|(mut bird, mut transform)| {
         transform.translation.x += bird.velocity.x * time.delta_seconds();
         transform.translation.y += bird.velocity.y * time.delta_seconds();

From 87dc4d031940196f63fb586598beb2942fcba071 Mon Sep 17 00:00:00 2001
From: Alex Saveau <saveau.alexandre@gmail.com>
Date: Thu, 24 Feb 2022 18:15:03 -0800
Subject: [PATCH 06/14] Address review feedback

Signed-off-by: Alex Saveau <saveau.alexandre@gmail.com>
---
 examples/tools/bevymark.rs | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/examples/tools/bevymark.rs b/examples/tools/bevymark.rs
index dc4f2eef304b1..d5378688e1c8c 100644
--- a/examples/tools/bevymark.rs
+++ b/examples/tools/bevymark.rs
@@ -8,7 +8,6 @@ use rand::{thread_rng, Rng};
 use std::fmt::Write;
 
 const BIRDS_PER_SECOND: u32 = 10000;
-const _BASE_COLOR: Color = Color::rgb(5.0, 5.0, 5.0);
 const GRAVITY: f32 = -9.8 * 100.0;
 const MAX_VELOCITY: f32 = 750.;
 const BIRD_SCALE: f32 = 0.15;
@@ -24,6 +23,9 @@ struct Bird {
     velocity: Vec3,
 }
 
+/// This example provides a 2D benchmark.
+///
+/// Usage: spawn more entities by clicking on the screen.
 fn main() {
     App::new()
         .insert_resource(WindowDescriptor {
@@ -221,8 +223,6 @@ fn spawn_birds(
 }
 
 fn movement_system(time: Res<Time>, mut bird_query: Query<(&mut Bird, &mut Transform)>) {
-    // Use for_each style iteration here and in the collision_system because it's faster thanks to
-    // better LLVM optimization opportunities (see transrangers) and hoisted branching.
     bird_query.for_each_mut(|(mut bird, mut transform)| {
         transform.translation.x += bird.velocity.x * time.delta_seconds();
         transform.translation.y += bird.velocity.y * time.delta_seconds();
@@ -262,6 +262,7 @@ fn counter_system(
 ) {
     let mut text = query.single_mut();
 
+    // Re-use string buffers here and below (clear + write) to save an allocation
     if counter.is_changed() {
         text.sections[1].value.clear();
         write!(text.sections[1].value, "{}", counter.count).unwrap();

From 0db3cdc6f82ec098e9119c470212ff305fb51618 Mon Sep 17 00:00:00 2001
From: Alex Saveau <saveau.alexandre@gmail.com>
Date: Thu, 24 Feb 2022 18:16:36 -0800
Subject: [PATCH 07/14] Oops, add back for_each comment

Signed-off-by: Alex Saveau <saveau.alexandre@gmail.com>
---
 examples/tools/bevymark.rs | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/examples/tools/bevymark.rs b/examples/tools/bevymark.rs
index d5378688e1c8c..6802cb48b14c2 100644
--- a/examples/tools/bevymark.rs
+++ b/examples/tools/bevymark.rs
@@ -223,6 +223,7 @@ fn spawn_birds(
 }
 
 fn movement_system(time: Res<Time>, mut bird_query: Query<(&mut Bird, &mut Transform)>) {
+    // `.for_each_mut` is faster than `.iter`, but can't be chained like a normal iterator.
     bird_query.for_each_mut(|(mut bird, mut transform)| {
         transform.translation.x += bird.velocity.x * time.delta_seconds();
         transform.translation.y += bird.velocity.y * time.delta_seconds();
@@ -235,6 +236,7 @@ fn collision_system(windows: Res<Windows>, mut bird_query: Query<(&mut Bird, &Tr
     let half_width = window.width() as f32 * 0.5;
     let half_height = window.height() as f32 * 0.5;
 
+    // `.for_each_mut` is faster than `.iter`, but can't be chained like a normal iterator.
     bird_query.for_each_mut(|(mut bird, transform)| {
         let x_vel = bird.velocity.x;
         let y_vel = bird.velocity.y;

From 212c4010c85ebc36ea0bad66e0cbb89b8501262b Mon Sep 17 00:00:00 2001
From: Alex Saveau <saveau.alexandre@gmail.com>
Date: Thu, 24 Feb 2022 18:40:54 -0800
Subject: [PATCH 08/14] Use usize instead of u128 so math isn't emulated

Signed-off-by: Alex Saveau <saveau.alexandre@gmail.com>
---
 examples/tools/bevymark.rs | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/examples/tools/bevymark.rs b/examples/tools/bevymark.rs
index 6802cb48b14c2..e027e16daadbc 100644
--- a/examples/tools/bevymark.rs
+++ b/examples/tools/bevymark.rs
@@ -14,7 +14,7 @@ const BIRD_SCALE: f32 = 0.15;
 const HALF_BIRD_SIZE: f32 = 256. * BIRD_SCALE * 0.5;
 
 struct BevyCounter {
-    pub count: u128,
+    pub count: usize,
     pub color: Color,
 }
 
@@ -57,8 +57,8 @@ fn main() {
 }
 
 struct BirdScheduled {
-    wave: u128,
-    per_wave: u128,
+    wave: usize,
+    per_wave: usize,
 }
 
 fn scheduled_spawner(
@@ -149,11 +149,11 @@ fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
     commands.insert_resource(BirdScheduled {
         per_wave: std::env::args()
             .nth(1)
-            .and_then(|arg| arg.parse::<u128>().ok())
+            .and_then(|arg| arg.parse::<usize>().ok())
             .unwrap_or_default(),
         wave: std::env::args()
             .nth(2)
-            .and_then(|arg| arg.parse::<u128>().ok())
+            .and_then(|arg| arg.parse::<usize>().ok())
             .unwrap_or(1),
     });
 }
@@ -172,7 +172,7 @@ fn mouse_handler(
     }
 
     if mouse_button_input.pressed(MouseButton::Left) {
-        let spawn_count = (BIRDS_PER_SECOND as f64 * time.delta_seconds_f64()) as u128;
+        let spawn_count = (BIRDS_PER_SECOND as f64 * time.delta_seconds_f64()) as usize;
         spawn_birds(
             &mut commands,
             &windows,
@@ -187,7 +187,7 @@ fn spawn_birds(
     commands: &mut Commands,
     windows: &Windows,
     counter: &mut BevyCounter,
-    spawn_count: u128,
+    spawn_count: usize,
     texture: Handle<Image>,
 ) {
     let window = windows.get_primary().unwrap();

From a2374b42a67ab8e22726fdef0ef39bb760674841 Mon Sep 17 00:00:00 2001
From: Alex Saveau <saveau.alexandre@gmail.com>
Date: Fri, 25 Feb 2022 09:54:39 -0800
Subject: [PATCH 09/14] Update examples/tools/bevymark.rs

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
---
 examples/tools/bevymark.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/examples/tools/bevymark.rs b/examples/tools/bevymark.rs
index e027e16daadbc..e3b9b0a7ef999 100644
--- a/examples/tools/bevymark.rs
+++ b/examples/tools/bevymark.rs
@@ -236,7 +236,7 @@ fn collision_system(windows: Res<Windows>, mut bird_query: Query<(&mut Bird, &Tr
     let half_width = window.width() as f32 * 0.5;
     let half_height = window.height() as f32 * 0.5;
 
-    // `.for_each_mut` is faster than `.iter`, but can't be chained like a normal iterator.
+    // `.for_each_mut` is faster than `.iter_mut`, but can't be chained like a normal iterator.
     bird_query.for_each_mut(|(mut bird, transform)| {
         let x_vel = bird.velocity.x;
         let y_vel = bird.velocity.y;

From f5c015e6b305008a7d64b5c8b4dd2cdeba833999 Mon Sep 17 00:00:00 2001
From: Alex Saveau <saveau.alexandre@gmail.com>
Date: Fri, 25 Feb 2022 09:54:48 -0800
Subject: [PATCH 10/14] Update examples/tools/bevymark.rs

Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
---
 examples/tools/bevymark.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/examples/tools/bevymark.rs b/examples/tools/bevymark.rs
index e3b9b0a7ef999..501428044454f 100644
--- a/examples/tools/bevymark.rs
+++ b/examples/tools/bevymark.rs
@@ -223,7 +223,7 @@ fn spawn_birds(
 }
 
 fn movement_system(time: Res<Time>, mut bird_query: Query<(&mut Bird, &mut Transform)>) {
-    // `.for_each_mut` is faster than `.iter`, but can't be chained like a normal iterator.
+    // `.for_each_mut` is faster than `.iter_mut`, but can't be chained like a normal iterator.
     bird_query.for_each_mut(|(mut bird, mut transform)| {
         transform.translation.x += bird.velocity.x * time.delta_seconds();
         transform.translation.y += bird.velocity.y * time.delta_seconds();

From 3146c531aa25513e711eb9d2a75361359b863ef8 Mon Sep 17 00:00:00 2001
From: Alex Saveau <saveau.alexandre@gmail.com>
Date: Fri, 25 Feb 2022 11:17:06 -0800
Subject: [PATCH 11/14] Disable vsync

Signed-off-by: Alex Saveau <saveau.alexandre@gmail.com>
---
 examples/tools/bevymark.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/examples/tools/bevymark.rs b/examples/tools/bevymark.rs
index 501428044454f..fe52edef43276 100644
--- a/examples/tools/bevymark.rs
+++ b/examples/tools/bevymark.rs
@@ -32,7 +32,7 @@ fn main() {
             title: "BevyMark".to_string(),
             width: 800.,
             height: 600.,
-            present_mode: PresentMode::Mailbox,
+            present_mode: PresentMode::Immediate,
             resizable: true,
             ..Default::default()
         })

From 0e3a0d3992cc5b3ce993bac048e955691ae1d535 Mon Sep 17 00:00:00 2001
From: Alex Saveau <saveau.alexandre@gmail.com>
Date: Sun, 27 Feb 2022 15:28:59 -0800
Subject: [PATCH 12/14] Address feedback

Signed-off-by: Alex Saveau <saveau.alexandre@gmail.com>
---
 examples/tools/bevymark.rs | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/examples/tools/bevymark.rs b/examples/tools/bevymark.rs
index fe52edef43276..b19475c065e30 100644
--- a/examples/tools/bevymark.rs
+++ b/examples/tools/bevymark.rs
@@ -5,7 +5,6 @@ use bevy::{
     window::PresentMode,
 };
 use rand::{thread_rng, Rng};
-use std::fmt::Write;
 
 const BIRDS_PER_SECOND: u32 = 10000;
 const GRAVITY: f32 = -9.8 * 100.0;
@@ -266,14 +265,12 @@ fn counter_system(
 
     // Re-use string buffers here and below (clear + write) to save an allocation
     if counter.is_changed() {
-        text.sections[1].value.clear();
-        write!(text.sections[1].value, "{}", counter.count).unwrap();
+        text.sections[1].value = format!("{}", counter.count);
     }
 
     if let Some(fps) = diagnostics.get(FrameTimeDiagnosticsPlugin::FPS) {
         if let Some(average) = fps.average() {
-            text.sections[3].value.clear();
-            write!(text.sections[3].value, "{:.2}", average).unwrap();
+            text.sections[3].value = format!("{:.2}", average);
         }
     };
 }

From 37a81204ab94a636f32b4540edd8f721841834f0 Mon Sep 17 00:00:00 2001
From: Carter Anderson <mcanders1@gmail.com>
Date: Sun, 27 Feb 2022 16:03:07 -0800
Subject: [PATCH 13/14] remove old comment

---
 examples/tools/bevymark.rs | 1 -
 1 file changed, 1 deletion(-)

diff --git a/examples/tools/bevymark.rs b/examples/tools/bevymark.rs
index b19475c065e30..7e7fd26594607 100644
--- a/examples/tools/bevymark.rs
+++ b/examples/tools/bevymark.rs
@@ -263,7 +263,6 @@ fn counter_system(
 ) {
     let mut text = query.single_mut();
 
-    // Re-use string buffers here and below (clear + write) to save an allocation
     if counter.is_changed() {
         text.sections[1].value = format!("{}", counter.count);
     }

From ddd219af37fe6c969037bbf399baf1f86d4aee09 Mon Sep 17 00:00:00 2001
From: Alex Saveau <saveau.alexandre@gmail.com>
Date: Sun, 27 Feb 2022 17:14:09 -0800
Subject: [PATCH 14/14] Go back to iter

Signed-off-by: Alex Saveau <saveau.alexandre@gmail.com>
---
 examples/tools/bevymark.rs | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/examples/tools/bevymark.rs b/examples/tools/bevymark.rs
index 7e7fd26594607..0157b4c5369ac 100644
--- a/examples/tools/bevymark.rs
+++ b/examples/tools/bevymark.rs
@@ -222,12 +222,11 @@ fn spawn_birds(
 }
 
 fn movement_system(time: Res<Time>, mut bird_query: Query<(&mut Bird, &mut Transform)>) {
-    // `.for_each_mut` is faster than `.iter_mut`, but can't be chained like a normal iterator.
-    bird_query.for_each_mut(|(mut bird, mut transform)| {
+    for (mut bird, mut transform) in bird_query.iter_mut() {
         transform.translation.x += bird.velocity.x * time.delta_seconds();
         transform.translation.y += bird.velocity.y * time.delta_seconds();
         bird.velocity.y += GRAVITY * time.delta_seconds();
-    });
+    }
 }
 
 fn collision_system(windows: Res<Windows>, mut bird_query: Query<(&mut Bird, &Transform)>) {
@@ -235,8 +234,7 @@ fn collision_system(windows: Res<Windows>, mut bird_query: Query<(&mut Bird, &Tr
     let half_width = window.width() as f32 * 0.5;
     let half_height = window.height() as f32 * 0.5;
 
-    // `.for_each_mut` is faster than `.iter_mut`, but can't be chained like a normal iterator.
-    bird_query.for_each_mut(|(mut bird, transform)| {
+    for (mut bird, transform) in bird_query.iter_mut() {
         let x_vel = bird.velocity.x;
         let y_vel = bird.velocity.y;
         let x_pos = transform.translation.x;
@@ -253,7 +251,7 @@ fn collision_system(windows: Res<Windows>, mut bird_query: Query<(&mut Bird, &Tr
         if y_pos + HALF_BIRD_SIZE > half_height && y_vel > 0.0 {
             bird.velocity.y = 0.0;
         }
-    });
+    }
 }
 
 fn counter_system(