I have been fighting a battle of optimization for a while now and it has been difficult to find a suitable approach to each situation. Before I began my journey into creating a moddable game with Game Maker: Studio I did do some research into how one might do such a thing. Believe it or not I could not find a single example aside from people just decompiling old Game Maker (6.0-8.1) games such as Hotline Miami and writing their own code.
That to me is ridiculous and if I recall accurately I believe it even breaks the Game Maker EULA. I wouldn't rely on users to break my game apart just to add to it. The majority of Game Maker users don't even have the slightest idea of how to actually create a moddable system (or simply believe it is not possible to do it optimally).