Prototype Lagging and Freezing

Hi, I’ve created a prototype that runs fine when viewing on a desktop browser. However when viewed on an iPhone browser there is significant lag, and after a few taps it freezes and become unresponsive (no blue rectangles showing you where to tap). Refreshing the page allows me to tap again, but then quickly runs into the same issue.

Unfortunately, for my desired audience I cannot rely on them installing the app, so viewing through a browser on mobile is what I need. Have tried reducing size of images, but to no avail. Does anyone have any tips for how to get it running smoothly? Thanks