Canvas drawImage() causes laggy with ion-content direction="xy"on iPad

Just creating a blank ionic project, add this in html

<ion-content direction="xy">
<canvas id="myCanvas" width="2481" height="1690"></canvas>

and this in app.js run()
var canvas = document.getElementById("myCanvas") if (canvas == null) return false; var context = canvas.getContext('2d'); var img=new Image(); img.onload = function() { context.drawImage(img,0,0); } img.src='img/Map.jpg';

working perfectly with android, but on iPad, obvious laggy can be noticed when move the image. Any workaround?

Is there anyone else has the same problem? Or just I miss_used something?