I am trying to understand baking in cycles and was wondering if I use a texture image with emission as input for material output, isn't it the same as baking? DO I need to bake this setup as well and then use that image instead of using the original texture image? My understanding is that baking is for all the material shaders and effects, but if I use a texture image already, then baking is not going to speed up rendering? Sorry if this sounds stupid, but I can't get my head around it.
If you use an image texture alone for your object, plugged into a diffuse or emission shader - that is as simple as it can be already. Baking is done to get complex information from a shader tree and multiple textures summed up in a few textures that can then be plugged into a Principled Shader.
If you are only needing the color information from the image texture you already have, baking isn't necessary.