How to optimize mobile game?

Phaser 3
1

Our team use phaser to build a slot game. But when we finished, we found the mobile game’s fps is too slow, 23fps in Android, 12 fps in iOS. And in PC web mobile test,it can work properly in 55fps.

I used to use renderTexture to draw image, but it couldn’t work. I have no idea, how to optimize the game? Anyone can help me,plz?

[gameconfig]

let game = this._phaserGame = new Phaser.Game(<Phaser.Types.Core.GameConfig>{
                width: 1920,
                height: 1080,
                scale: {
                    mode: Phaser.Scale.FIT,
                    autoCenter: Phaser.Scale.CENTER_BOTH
                },
                autoFocus: true,
                type: Phaser.WEBGL,
                canvas: this._mainCanvas,
                scene: [{
                    preload: function () {
                        if (popcorn.Platform.isMobile) {
                            _self.resizeCanvas();
                        }
                        else {
                            _self.repositionCanvas();
                        }
                    },
                    create: function () {
                        (<Phaser.Scene>this).scene.start('prepareScene');
                    }
                }, mainScene, loadingScene, preLoadingScene, prepareScene],
                title: 'Popcorn framework',
                url: '',
                backgroundColor: 0x123456
            });