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).
From a rendering perspective, c2 can handle way more than 200 objects on desktop machines (unless each instance has it's own shader). Offscreen objects aren't rendered, so they don't impact rending performance at all.
Code wise, there are plenty of things that can be done to improve performance if it's a problem, like as Katala mentioned, you can disable collisions on faraway objects, and you can also disable offscreen instances of enemies as well. You could even come up with a system for creating and destroying the level as you go through it.
1024 textures aren't a problem for any remotely modern graphics card, even old integrated intel ones. If you're having lousy performance on an old card, it's probably because the card has been blacklisted and it's rendering via software. You can test it by disabling the driver blacklist in chrome. Technically, you can disable the driver blacklist in node webkit as well, but doing so can cause glitches as cards are blacklisted for a reason.