I developed a game app using Phaser.js. I sort of put the code into Ionic blank starter app. So basically the
You can make it work. BUT ... there is no support for WebGL on any Android device using the stock webview (Ionic uses Cordova to package the app which is then being run inside a webview on the device): http://caniuse.com/#feat=webgl
Phaser.js is built on top of Pixie.js which will fall back to 2D canvas rendering. That's why your game is running slow.
If you want to use Ionic and WebGL you should build your app using CrossWalk. I have done that and it is awesome: https://crosswalk-project.org/
There's other options such as CocoonJS to get WebGL going, but I haven't used those myself.