How does installing XCode, Visual Studio and Unity on my mac impact my computer's speed? Most of the time I use my mac computer for graphics design but I enjoy coding too. Since clean-installing macOS a few months ago, I avoided installing XCode, Unity and Visual Studio for fear that with all their dependencies, they might bog down my aging computer.

However I wonder whether this is the actual case given that osx apps tend to be statically linked and self-contained.

Do these three Dev Tools slow my computer down somehow by their mere existence, or is it only disk space that they occupy when I am not using them?
No, they do not slow your computer down by their mere existence. Yes, they will occupy disk space.

It hasn't got anything to do with them being statically linked.