Have you taken the time and effort to test on mobile first? This is the main issue with problems like these. You stated that performance on your computer is great, that's to be expected. On mobile, well that's where you have to be more concerned about performance with Construct 2.
I suggest you test on mobile. Make changes with your events, possibly change the size of your images, compress them, if you're using particles lessen the rate or size. It could be a range of things.
Also, what did you export with? If you haven't tried already, export your project with CocoonJS and put the ZIP folder on your phone. Download the CocoonJS App Launcher on your phone as well. Launch your game via the App Launcher by selecting Canvas+, when you have the ZIP folder selected. This is for testing, if you wanna compile with CocoonJS, go ahead and do that too, if you wish.