I've never subscribed to C3 but used C2 previously, thought I'd checkout the forum and low and behold one of the first posts is to do with performance, not that this is going to be helpful in anyway, but it's yet another forum post on the performance issues that has plagued Construct since C2, it doesn't matter what the dev's say regarding html5 tech, they keep saying compatibility or performance is better with latest mobile tech, it still doesn't help the fact that html5 performance was and appears still to be terrible on those mobile formats & don't even think about larger projects, look at the debacle of 'The Next Penelope'.
I'm not knocking the engine as a development tool, as i'm still to see any engine you can get something playable built so quickly, but it seems its the final hurdle every time with Construct, always performance issues. If I get back into development it will be with a tool that has native exporters all the way, I just can't be done with the wrappers workaround.
Hope you can get it worked out.