Is Blender the only open source Non-destructive editor? Blender's "Nodes" function seems to make it a non-destructive editor.

The "Mix" node enables the user to composite using "blend modes".
For me, the "Add" blend mode is the most important of these blend modes but often it the Add blend mode is not included in compositing tools.
This and the fact that Blender is seemingly non-destructive is the reason I'm using Blender.

I am currently using Blender as a 2D compositor only, meaning that my "RenderLayers" nodes provide Blender with an image that mocks a 2D vector (as though I were using Adobe After Effects's "Shapes" tool to composite onto image/video). I have always to ensure the camera is pointing 100% downwards i.e. in-line with the z-axis.

The problem is that Blender takes a long time to composite; The whole process seems extremely inefficient when I compare Blender with Adobe After Effects.

Please could you advise me on whether I should quit using Blender for this application?
Thank you for your time
If the problem is only performance, Blender can also leverage OpenCL running on the GPU and CPU to speed up the node compositing. From my experience, it significantly speeds up the process.

You can turn it on in the node editor panel.