Edge project slowing down

Hey there,

I've been recreating a Flash project in Edge (so that it can run on mobile devices). It's a "pre-lab" for students here at our university, where the student can go through a chemistry lab before actually doing the real world lab.

I've laid it out roughly from beginging to end, but when I run it on different browsers on a mac, pc or iPad2 the button clicks become slower and slower in response (as if it's running out memory) halfway through the prelab.

I've stripped back all the graphics off the timeline except for the important buttons and it still does the same thing. Do I need to delete all non-related images and symbols out of the Assets window? Or is it because I've been using transparent png's and should be using SVG's (but that doesnt answer why it's still slow when I strip back the project).

The only errors I'm getting in Chrome's Console is this:

Would this be why it's slowing down?

Thanks in advance,