diff --git a/src/fireworks.rs b/src/fireworks.rs
index 1d93306..cce2867 100644
--- a/src/fireworks.rs
+++ b/src/fireworks.rs
@@ -1,6 +1,6 @@
 //! `firework` module provides functions to define, create and update fireworks
 
-use std::time::{Duration, SystemTime};
+use std::{collections::VecDeque, time::{Duration, SystemTime}};
 
 use glam::Vec2;
 use rand::{seq::IteratorRandom, thread_rng};
@@ -373,8 +373,6 @@ pub enum FireworkInstallForm {
     DynamicInstall,
 }
 
-fn init_trail(init_pos: Vec2, n: usize) -> Vec<Vec2> {
-    let mut res = Vec::new();
-    (0..n).for_each(|_| res.push(init_pos));
-    res
+fn init_trail(init_pos: Vec2, n: usize) -> VecDeque<Vec2> {
+    VecDeque::from(vec![init_pos; n])
 }
diff --git a/src/particle.rs b/src/particle.rs
index d40e2ec..3eef7b4 100644
--- a/src/particle.rs
+++ b/src/particle.rs
@@ -1,6 +1,6 @@
 //! `particle` module provides functions to define, create and update particles
 
-use std::time::Duration;
+use std::{collections::VecDeque, time::Duration};
 
 use glam::Vec2;
 
@@ -23,7 +23,7 @@ pub struct Particle {
     pub pos: Vec2,
     pub vel: Vec2,
     /// Records a `trail_length` of previous positions of the `Particle`
-    pub trail: Vec<Vec2>,
+    pub trail: VecDeque<Vec2>,
     pub life_state: LifeState,
     /// `Duration` since initialization of this `Particle`
     pub time_elapsed: Duration,
@@ -35,7 +35,7 @@ impl Default for Particle {
         Self {
             pos: Vec2::ZERO,
             vel: Vec2::ZERO,
-            trail: Vec::new(),
+            trail: VecDeque::new(),
             life_state: LifeState::Alive,
             time_elapsed: Duration::ZERO,
             config: ParticleConfig::default(),
@@ -52,8 +52,7 @@ impl Particle {
         life_time: Duration,
         color: (u8, u8, u8),
     ) -> Self {
-        let mut trail = Vec::with_capacity(trail_length);
-        (0..trail_length).for_each(|_| trail.push(pos));
+        let trail = VecDeque::from(vec![pos; trail_length]);
         let life_state = LifeState::Alive;
         Self {
             pos,
@@ -97,8 +96,8 @@ impl Particle {
             self.pos += TIME_STEP * self.vel;
             t += TIME_STEP;
         }
-        self.trail.remove(0);
-        self.trail.push(self.pos);
+        self.trail.pop_front();
+        self.trail.push_back(self.pos);
     }
 }
 
diff --git a/src/term.rs b/src/term.rs
index b665db1..9b764af 100644
--- a/src/term.rs
+++ b/src/term.rs
@@ -284,13 +284,11 @@ fn get_char_alive(density: f32, cjk: bool) -> char {
         } else {
             "oahkbdpqwmZO0QLCJUYXzcvunxrjft*"
         }
-    } else {
-        if cjk {
+    } else if cjk {
             "𰻞"
             // "東京福岡横浜縄"
         } else {
             "$@B%8&WM#"
-        }
     };
     palette
         .chars()
@@ -319,13 +317,11 @@ fn get_char_declining(density: f32, cjk: bool) -> char {
         } else {
             "/\\| ()1{}[ ]?"
         }
-    } else {
-        if cjk {
+    } else if cjk {
             "繁荣昌盛国泰民安龍龖龠龜耋"
             // "時間言葉目覚"
         } else {
             "xrjft*"
-        }
     };
     palette
         .chars()
@@ -340,13 +336,11 @@ fn get_char_dying(density: f32, cjk: bool) -> char {
         } else {
             ".  ,`.    ^,' . "
         }
-    } else {
-        if cjk {
+    } else if cjk {
             "|￥人 上十入乙小 下"
             // "イントマトナイフ"
         } else {
             " /\\| ( )  1{} [  ]?i !l I;: ,\"^ "
-        }
     };
     palette
         .chars()