More materials or more instances?

Hello! I’m working on a project, and i have a lot of meshes i need to import.For them, I would need 3 base materials, and then instances would do it for all of them.Instead, i can also create a single base material, using switch parameters, and with this material, i can create instances for all my meshes.Naturally, the quality is the same, the problem is that the latter one uses 5 more instructions, compared to my “cheapest” material from the other three.In other words, i can either use 3 basic materials that have 5-6 less instructions each and create instances, or use a single one with more instructions for everything.Which is better for the performance? as far as i know, only the base material compiles, and no other instance, but is it worth it even if it has a little more instructions?
One more thing: In a material, which is better for the performances: to use a VertexColor input or a premade map, for creating a mask?

If you use switch parameters, the amount of instructions depends on their true/false states, and if its only 5 more instructions there is nothing to worry about. The advantage does come when you use multiple instances, as they can (If my understanding is fully correct) share calculations that are the same among multiple instances.
My guess (without testing this case) would be that even though the performance gain is very minimal, using one master over 3 is better.

It does depend on how those three base materials are set up though, if you need 90% new calculations per true/false state it might not be worth it. But if you are sharing most of the nodes, and only a few new nodes come into play with true/false states it should be worth it.

In the end its both workflow and optimization. how much time do you gain using the one master material over three?

As the performance on vertex color and texture mask, its the same thing.
How many vertex colors, if you have a 4096/4096 texture for masks, that would be a significant hit on vram usage.

I personally would go what you feel most comfortable with/fastest route.