Mantra shaders are highly optimized if you have your component in clearly defined if blocks for instance. And can be easy to wire together if you use bsdf based sub-components, and/or structs. This is currently the only option for a co-shader equivalent, but if your a renderman person vops and is the most similar to slim, while shops and slim aren't really even close. IMO Shops could be discontinued in that concept, but legacy people would go crazy.I've had several iterations of ubershader in production with 30,000 parameters UI thanks to a hidden UI design that rendered very minimally(SideFX did increase the hidden cap a while back).Of course if you flip on every switch the shader it will render slower. If your rendering a diffuse lambert it will take the same amount of time as a vop shader with just diffuse codes. It compiles the vfl on the fly if the save as code check box is not on, other wise it's compile if you do. The best thing is that for that 90% that was spoken of already, you use the same shader for all materials. This allows you to have a library of default presets once fine tuned work across multiple productions. Lighting the same metal becomes extremely easy. You just need one shader guy, and you can hire a bunch of cheap lighters. God praise artist(sarcasm), but if you have too many hands in the pot you'll get way to many settings for the same material that lights differently. And lots of time spent debugging the same concepts over and over again.