Or simply is HTML5's or wrapper's fault. Come on, today we can run 1080p/4k content and play HD games without any issue on our phones, but can't run a f*cking 2D game, we need to optimize the s*it out of it ?
I feel your frustration. I'm testing my project on an intel hd4000 laptop (the kind that a kid might own...) and I'm struggling to maintain 60 fps in Chrome with only a few on-screen sprite blending effects (960x540 integer scaling). The back-to-front renderer used in c2 will always be problematic for performance on low end devices (I recall a front-to-back renderer failed beta - and I never understood why an orthographic 3d camera was not chosen to take advantage of gpu 3d support...). Anyway, I've been using c2 as a hobbyist for 5 years now and it's proven to be a superb tool for learning and prototyping... But some elements feel incomplete and don't appear to ever be updated (shadowlight: one per layer! / no platform collision filtering / physics lacks many box2d features / asm.js physics joints can be inexplicably stretchy / etc).
But as far as exporting a project as a commercial entity to anywhere beyond the likes of Newgrounds/Kongregate (without full api support), c2 users will always be at the mercy of wrappers and the associated never ending cycle of updates, bugs, and updates, and... etc. I suspect that these things will be the same in another 5 years - as browser tech changes the wrappers will always be playing catch-up (anyone remember Impact.js & cocoonjs..?).
I will continue to use c2 with joy to complete my current multiplayer project and for tinkering with game ideas, just because the event system is amazingly intuitive and it's ideal for prototyping. Perhaps, in 5 years, the novelty of html5 will have reduced and in-browser performance will permit a more stable 60 fps (ie webgl export) for c2 games. But all of these are why I just bought Playmaker...
So, to the OP, find something you will enjoy using - a tool that won't be beyond your abilities and will allow you to realise your dreams - and get stuck in. Just make sure you test on your target hardware to ensure that you don't become unexpectedly disappointed.