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Topics - Pacifico

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Java / 15%-20% CPU usage when drawing a grid
« on: February 05, 2014, 07:11:44 am »

I decided to attempt a quick version of Conway's Game of Life to familiarize myself with JSFML. I noticed when simply drawing a grid of rectangles, my CPU usage will spike up to 15%-20% on my i5-3570K. Would anyone be able to tell me what I am doing wrong? This amount of CPU usage for a grid seems excessive, and I'm wondering if the draw calls are being performed by the CPU, instead of the GPU, or if they aren't being batched the way I imagine.

Here's the code I am using to reproduce the issue. If I add
to my code, the CPU usage will spike up to 25%-30%! I appreciate any help!

import org.jsfml.graphics.Color;
import org.jsfml.graphics.RectangleShape;
import org.jsfml.graphics.RenderWindow;
import org.jsfml.system.Vector2f;
import org.jsfml.window.VideoMode;
import org.jsfml.window.event.Event;

public class GameOfLife {
    private RenderWindow window;
    private RectangleShape rectangle;
    private final static int WIDTH = 64;
    private final static int HEIGHT = 48;
    private final static int SIZE = 10;

    public GameOfLife() {
        window = new RenderWindow(new VideoMode(640, 480), "Game of Life");

        rectangle = new RectangleShape(new Vector2f(SIZE, SIZE));

    public void run() {
        while (window.isOpen()) {

    private void processEvents() {
        for (Event event : window.pollEvents()) {
            switch (event.type) {
                case CLOSED:

    private void update() {

    private void render() {

        for (int row = 0; row < HEIGHT; row++) {
            for (int column = 0; column < WIDTH; column++) {
                int x = column * SIZE;
                int y = row * SIZE;
                rectangle.setPosition(x, y);


    public static void main(String[] args) {
        (new GameOfLife()).run();

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