I had issues with large numbers of objects, textures and events. Large textures add a lot to the preview theme, and though that gets cached, any time you update the graphics they need to get recompiled, on my game with 10,000 events it takes 10 minutes to load the battle system event sheet, 7 seconds of waiting for every single edit made to that event sheet, 30 minutes to undo or delete an object, 5 minutes to preview, there are events I can't move or edit without crashing the editor, I have to repeatedly close and restart the program when using the animation editor to keep memory leaks from crashing the program, the runtime sometimes crashes, and CC can become very unstable by trying to do things like delete family variables or such which kept me from reworking the code.
There are more issues too, like don't use the layout object, but I can't remember them all ATM. C2 supports larger projects better and is still being supported so any problems you discover can be fixed, and it can also export to exe with node webkit so you can make desktop games for PC, Mac and Linux. C2 even renders faster than CC does!