diff --git a/README.md b/README.md
index 8122e27..1d6aa9b 100644
--- a/README.md
+++ b/README.md
@@ -8,7 +8,7 @@ A classic implementation of the Pong game developed specifically for the Arduino
 
 # 📹 Preview
 
-![Pong](preview.png)
+![Pong](assets/preview.png)
 
 Youtube: https://youtu.be/ouLBTDjpKqc
 
diff --git a/arduino_pong.ino b/arduino_pong.ino
index 90d04a4..36fb857 100644
--- a/arduino_pong.ino
+++ b/arduino_pong.ino
@@ -30,7 +30,7 @@ int ball_y= BALL_RESET_Y;
 
 int need_refresh= 1;
 
-int loop_delay= INITIAL_LOOP_DELAY;
+int ball_delay= INITIAL_BALL_DELAY;
 
 long exec_t2= millis();
 
@@ -51,11 +51,14 @@ void loop() {
   long exec_t1= millis();
   pong_move_p1(p1_start, need_refresh);
   pong_move_p2(p2_start, need_refresh);
-  render_matrix(frame, p1_start, p2_start, need_refresh, ball_x, ball_y);
-  if (exec_t1 - exec_t2 > loop_delay) {
-    move_ball(ball_x, ball_y, loop_delay, p1_start, p2_start, need_refresh);
+  if (exec_t1 - exec_t2 > ball_delay) {
+    move_ball(ball_x, ball_y, ball_delay, p1_start, p2_start, need_refresh);
     exec_t2= exec_t1;
   }
-  matrix.renderBitmap(frame, MATRIX_HEIGHT, MATRIX_WIDTH);
+  if (need_refresh) {
+    render_matrix(frame, p1_start, p2_start, ball_x, ball_y);
+    matrix.renderBitmap(frame, MATRIX_HEIGHT, MATRIX_WIDTH);
+    need_refresh= 0;
+  }
   delay(50);
 }
diff --git a/preview.png b/assets/preview.png
similarity index 100%
rename from preview.png
rename to assets/preview.png
diff --git a/config.h b/config.h
index 026b4c5..05245b9 100644
--- a/config.h
+++ b/config.h
@@ -8,4 +8,4 @@
 #define BALL_RESET_X (MATRIX_WIDTH / 2)
 #define BALL_RESET_Y (MATRIX_HEIGHT / 2)
 #define BAR_LENGTH 3
-#define INITIAL_LOOP_DELAY 200
+#define INITIAL_BALL_DELAY 200
diff --git a/pong_ball.cpp b/pong_ball.cpp
index f4fabc3..f7c9139 100644
--- a/pong_ball.cpp
+++ b/pong_ball.cpp
@@ -13,7 +13,7 @@ int p2_score= 0;
 int ball_move_x= 0;
 int ball_move_y= 0;
 
-void point_scored(int &ball_x, int &ball_y, int &loop_delay) {
+void point_scored(int &ball_x, int &ball_y, int &ball_delay) {
   ball_x= BALL_RESET_X;
   ball_y= BALL_RESET_Y;
   Serial.print("P1: ");
@@ -24,10 +24,10 @@ void point_scored(int &ball_x, int &ball_y, int &loop_delay) {
   Serial.println();
 
   hits= 0;
-  loop_delay= INITIAL_LOOP_DELAY;
+  ball_delay= INITIAL_BALL_DELAY;
 }
 
-void move_ball(int &ball_x, int &ball_y, int &loop_delay, int p1_start, int p2_start, int &need_refresh) {
+void move_ball(int &ball_x, int &ball_y, int &ball_delay, int p1_start, int p2_start, int &need_refresh) {
   need_refresh= 1;
   if (ball_x < 0 || ball_x > MATRIX_WIDTH-1 || ball_y < 0 || ball_y > MATRIX_HEIGHT-1) {
     // ball out of matrix limits
@@ -52,7 +52,7 @@ void move_ball(int &ball_x, int &ball_y, int &loop_delay, int p1_start, int p2_s
       // else p2 score, reset board
       p2_score += 1;
       Serial.println("Player 2 Scores");
-      point_scored(ball_x, ball_y, loop_delay);
+      point_scored(ball_x, ball_y, ball_delay);
     }
     else {
       hits += 1;
@@ -64,7 +64,7 @@ void move_ball(int &ball_x, int &ball_y, int &loop_delay, int p1_start, int p2_s
       // else p1 score, reset board
       p1_score += 1;
       Serial.println("Player 1 Scores");
-      point_scored(ball_x, ball_y, loop_delay);
+      point_scored(ball_x, ball_y, ball_delay);
     }
     else {
       hits += 1;
@@ -77,10 +77,10 @@ void move_ball(int &ball_x, int &ball_y, int &loop_delay, int p1_start, int p2_s
     ball_move_y= ball_move_y * -1;
   }
 
-  if (hits >= 6 && loop_delay >= 80) {
+  if (hits >= 6 && ball_delay >= 80) {
     // increase ball speed
     hits = 0;
-    loop_delay -= 20;
+    ball_delay -= 20;
   }
 
   ball_x+= ball_move_x;
diff --git a/pong_render.cpp b/pong_render.cpp
index d0ae525..01830a2 100644
--- a/pong_render.cpp
+++ b/pong_render.cpp
@@ -1,9 +1,7 @@
 #include <Arduino.h>
 #include "config.h"
 
-void render_matrix(byte frame[MATRIX_HEIGHT][MATRIX_WIDTH], int p1_start, int p2_start, int &need_refresh, int ball_x, int ball_y) {
-  if (!need_refresh) return;
-  need_refresh= 0;
+void render_matrix(byte frame[MATRIX_HEIGHT][MATRIX_WIDTH], int p1_start, int p2_start, int ball_x, int ball_y) {
   // clear
   for (int x=0; x < MATRIX_WIDTH; x++) {
     for (int y=0; y < MATRIX_HEIGHT; y++) {
diff --git a/pong_render.h b/pong_render.h
index ed6a2b5..11710f9 100644
--- a/pong_render.h
+++ b/pong_render.h
@@ -4,6 +4,6 @@
 #include <Arduino.h>
 #include "Arduino_LED_Matrix.h"
 
-void render_matrix(byte frame[MATRIX_HEIGHT][MATRIX_WIDTH], int p1_start, int p2_start, int &need_refresh, int ball_x, int ball_y);
+void render_matrix(byte frame[MATRIX_HEIGHT][MATRIX_WIDTH], int p1_start, int p2_start, int ball_x, int ball_y);
 
 #endif