"But I was told that C2/C3 is nearly as fast as native, so maybe we just need something even fastesterest!"
Sarcasm aside, this has always been a slight issue, it might be worse "again" now, but it was always there hiding under the Chromium runtime, and Google has made it pretty clear they don't care enough to fix it for game engines built on their platform.
Overall I just find it really ironic that the reason we left the native realm was to avoid driver issues, and now we're facing issues that are basically the software/sandbox equivalent of drivers, and once again Scirra and by extension their customers / us are left throwing all our hands up saying "It's not our game/engine, it's the platform we're building on!"
HTML5 will improve, it has already improved a tonne from when us CC users first tried C2 betas, but I don't think Google's going to save the day here. Scirra needs to invest some of that sweet C3 sub money into a proper runtime of their own for HTML5/JS that runs on all platforms. That's when they'll have the winning combination of killer editor and amazing runtime.