Phew, thank you, but that raise more questions. Now, when I know what to look for, I see NW.js is also used as one and only way to make Windows executable. I though, C2 is producing actual standalone binaries for the Windows, plus maybe with some dll dependencies, DirectX etc. Though this suggests, the game will always run through intermediate code using NW.js as the wrapper, which is basically the Chrome. However, as the NW.js seem to be the only way to make Windows executable and I've seen some pretty complex games made with C2 that had no issues with the performance, I guess it's alright not to worry about the performace beforehand.
As far as I know NW.js is currently the only make to produce a Win binary executable with C2, I have yet to have a performance issue with C2 using the nwjs wrapper but I also focus heavily on performance and the weight of my gfx, sfx etc.
I.E. as soon as I build a mechanic for a game I immediately do a play-test and then look to see if there is anyway I can possibly optimize or shorten anything in said mechanic. But that is just my habit.
Also there are plenty of resources on keeping your game optimized in C2.
https://www.scirra.com/blog/83/optimisa ... -your-time
http://www.burquitlambadgers.com/2015/0 ... ance-tips/