Very interesting observations about groups. I had no idea they impacted performance, as I use them only for organisational purposes, not for switching events on and off. Certainly something to be aware of.
jayderyu, so are you saying that if C2 had been designed to be more objected orientated, with event sheets being attached to objects rather than scene level, then it would potentially have much better performance? Would be a nice option to have it both ways, but I guess that would require a complete architectural change. One of the things that is cool about Godot is that you can attach scripts at the scene level or the object level, which gives you a lot of creative options. GMS can certainly get confusing at times, when you come back to an old project and wonder where the hell you attached your code!
Would have been interesting if C2 had gone down the Haxe/OpenCL path, but if the compile time is anything like Stencyl 3 then maybe not the best idea.
I still think Scirra should hire an extra dev to just do native exports (most people just want Android/IOS/Windows in addition to html5) and then charge $100 for each exporter. It would solve a lot of problems.
serpent ....If you want to go down the open source path, I would steer clear of Torque. Try the new Godot Engine, or even Enigma, which is a GMS clone. Or the free GameDevelop, which is very C2-like, but not as good.