first of all, you need to test your game using cocoonjs now, and the performance tips you already read is very useful. I follow it and tested using cocoonjs , it's really work.
1. If your game have a moving enemy on the layout, just disable them, make them stand and if your character come near enemy, they'll chase and attack, because too many enemy moving in runtime will cause down performance.
2. I draw my level and cut it apart. 500x500px is fine, then import into construct. ( i don't use tile background, just sprite)
3.Don't use too many text box on screen, it's cause down the fps too.
It's midnight now, i need some sleep, i will share more in the morning :))