Thanks for the comments.
It's an arcade style game so it's not filled with massive bloated levels, it's designed to be replayed a bit. The only problems I've had with node-webkit is the Mac version has mostly all black/gray graphics (whereas it runs fine in Chrome for Mac) so I'm hoping that eventually it'll be upto par with Chrome.
And the only problems with C2 projects I have is keeping the objectcount to around 100-200~ (which means coming up with creative ways to limit objects that aren't being seen, I think that's usually good count? but 
Arima probably knows more in this than I do) so that it will run well on most things. However to keep the object count low I did use a number of large textures (1000x1000) too which probably doesn't run great on old intel/integrated graphic systems (I think I use less than 100mb of memory in total, last I remember).
The code can impact it a lot, eg: like doing to many collision checks with a lot of objects, but I learnt a ton from finishing this game so I imagine it'll be a heap easier to make my events less bloated and more efficient next time. For my next game, I've started using the preview on lan feature with my tablet which helps keep things in check.