我创建了一个问题的简单版本
JSFiddle Example

每个图块都是一个Shape并被缓存.
所有形状都进入容器内,容器根据摄像机位置移动.

我注意到某些缩放级别的fps有奇怪的下降.
缩放只是调整形状的大小.

如果您调整缩放,您将看到我的意思.

铬

zoom 1 =好的fps
zoom 3 =糟糕的fps
zoom 5 =好的fps

这种帧速率问题的原因是什么？

请注意,我已经在createjs社区论坛上发布了这个.
Community Question

这是jsfiddle示例中的代码

HTML

<canvas id="mainCanvas" width="500" height="500"></canvas>
<span id="fps-container"><span id="fps">Loading</span> FPS</span>

JS

/*
This is a very simple version of a larger app/game i am creating
uses a large map that is drawn in sectors (createjs shapes)
I have not figured out the best way to cache,because if i cache all at once,its a lot of overhead.

My main issue is the zoom levels,the zoom simply adjusts the sectorsize.
The problem with this is that there seems to be a wierd performance problem at certain zoom levels.

To test this out,adjust the camera zoom property. I do not recommend anything more that 6.
*/

//Generic Settings
var Settings = {
    block_size: 50,rows: 50,cols: 50
}

//Create Camera
var Camera = {
    /*

    HERE IS THE ZOOM PROBLEM

      Chrome
      zoom : 1 = good fps
      zoom : 2 - 4 = bad fps
      zoom : 5 - 6 = good fps again ... wtf

      Safari
      Zoom: 7 = Good fps

  */
    x: 0,y: 0,zoom:1
}

//Create Short Alias
var Stage = createjs.Stage;
var Ticker = createjs.Ticker;
var Container = createjs.Container;
var Graphics = createjs.Graphics;
var Shape = createjs.Shape;


//Full Screen Canvas
var canvas = document.getElementById("mainCanvas");
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;

//Create Stage
var mainStage = new Stage(canvas);
mainStage.snameToPixelsEnabled = true;
mainStage.autoClear = true;

//Start Ticker
Ticker.addListener(this);
Ticker.useRAF = true;
Ticker.setFPS(30);

//Create Container;
var mainContainer = new Container();
mainContainer.snapToPixel = true;

//Add Container to Stage
mainStage.addChild(mainContainer);


//Create Lots of Shapes
var size = Settings.block_size * Camera.zoom;

//For the purpose of demonstration,I am only creating a square
//My actual app has much more complex drawings
var graphics = new Graphics();
graphics.setStrokeStyle(1 * Camera.zoom,"round");
graphics.beginFill(Graphics.getRGB(230,230,0.5));
graphics.beginStroke(null);
graphics.rect(-10,-10,size+10,size+10);


var cols = Settings.cols;
var rows = Settings.rows;
for (var x = 0; x < cols; x++) {
    for (var y = 0; y < rows; y++) {

        var shape = new Shape(graphics);
        shape.x = x * size;
        shape.y = y * size;

        //Cache the shape,(the offset is to prevent the cache from chopping off complex shapes)
        var cache_offset = 10 * Camera.zoom;
        shape.cache(-cache_offset,-cache_offset,size + cache_offset,size + cache_offset);

        //Add shape to container
        mainContainer.addChild(shape);
    }
}

//Make map draggable
var lastX,lastY;

mainStage.onMouseDown = function(evt){
    lastX = evt.stageX;
    lastY = evt.stageY;
}

mainStage.onMouseMove = function(evt){
    if(lastX && lastY){
        var stageX = evt.stageX;
        var stageY = evt.stageY;
        var diffX = lastX - stageX;
        var diffY = lastY - stageY;
        lastX = stageX;
        lastY = stageY;
        Camera.x += diffX / Camera.zoom;
        Camera.y += diffY / Camera.zoom;
    }    
}

mainStage.onMouseUp = function(evt){
    lastX = null;
    lastY = null;
}

//Update the container position based on camera position and zoom
updatePosition = function(){
    mainContainer.x = -Camera.x * Camera.zoom;
    mainContainer.y = -Camera.y * Camera.zoom;
}


tick = function(){
    updatePosition();
    mainStage.update();
    var fps = document.getElementById('fps');
    fps.innerHTML = Ticker.getMeasuredFPS();
}