This is most evident in the fact that over time, performance with CocoonJS using C2-created programs has gotten worse. I wouldn't be surprised if Ludei announced over the next few weeks that they are dropping support for C2, because this is what it seems like they are doing. Every new update they post promises new features, enhancements, and performance improvements, and recently every new update has resulted in C2 programs losing performance.
"Drop support in the next few weeks"? Drama much?
I don't know what you're testing with because for me I've gotten double performance increase from 1.3 to 1.4 and a further increase from 1.4 to 1.4.1, both on new and old smartphones. Of course, that is Android so iOS might vary.
Also It's not Construct 2 to CocoonJS export that "struggles".
Before 1.4 we used the Web-based physics engine.
With 1.4 they also enabled, in addition, the Accelarated engine. The problem was that it was missing a few libraries that were in the Web Based engine, but those are now added.
Seems like a weird issue. I'll check it out later after work. I don't remember ever encountering this.