diff --git a/src/modules/picture.js b/src/modules/picture.js
index 41933b9..f65a504 100644
--- a/src/modules/picture.js
+++ b/src/modules/picture.js
@@ -50,12 +50,13 @@ export function picToBoard(pixels) {
 // convert board to ImageData
 // TODO : different cell to color functions
 // (binary, intermediate states, camaieux, etc)
-export function boardToPic(board) {
+export function boardToPic(board, frame) {
   const live = board.cellProperties.liveColor;
   const dead = board.cellProperties.deadColor;
-  const img = new ImageData(board.width, board.height);
+  const img = frame || new ImageData(board.width, board.height);
   const colors = [hexToRGB(live), hexToRGB(dead)];
   board.grid.reduce((acc, cell, index) => {
+    if (cell.state === cell.prevState) return acc;
     const color = colors[(cell.state === 1) & 1];
     const i = index * 4;
     acc[i] = color[0];
diff --git a/src/modules/renderer.js b/src/modules/renderer.js
index a720ff8..a49c9d3 100644
--- a/src/modules/renderer.js
+++ b/src/modules/renderer.js
@@ -9,18 +9,20 @@ class Renderer {
     this.height = null;
     this.ctx = null;
     this.refreshRate = 300;
+    this.prevFrame = null;
   }
 
   // draws the board representation on the canvas
   render(board) {
     const d = board.cellProperties.size;
     // bool to RGBA colors
-    const img = boardToPic(board);
+    const img = boardToPic(board, this.prevFrame);
     this.ctx.clearRect(0, 0, this.width, this.height);
     scaleAndApply(this.ctx, d, () => {
       this.workCtx.putImageData(img, 0, 0);
       this.ctx.drawImage(this.workCanvas, 0, 0, this.width, this.height);
     });
+    this.prevFrame = this.workCtx.getImageData(0, 0, board.width, board.height);
   }
 
   // draw image on canvas