I'm actually going to close the case and branch a separate discussion to the Developer space, since cases work differently than normal discussions and will cause "weird" things to happen when moved.
Sorry i dont know about that. Yes, you could close this case, and create another discussion.
As a plugin runs within Jive it's usually Java. I have no idea whether class loading works fine if you add a native library - Anyhow writing a plugin code within C and then wrapping a lot of things into Java may be hard - and there is likely no performance gain.
Apps which use the REST API can run on random remote servers and thus you can use every programming language you want.
Not only can you use other programming languages, but, as implied, they run outside the jive process, which is another benefit.