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You are right there is a lot of noise on the image you shared which is not caused only by lights but from reflective-materials as well.
Have you used Global Illumination by the way - some parts of the scene are too dark so it is probably turned off.
VrayLightMtl is useful for surfaces emitting light - however a good practice is to use it in combination with some kind of light in order to produce faster and smoother result.
You could also use it alone if Direct Illumination option is turned on - but it will require a lot of samples in order to generate smooth result.
In this case I would use VrayLightMtl with Direct Illumination OFF for the light-geometry and a VrayLight or SpotLight with VrayShadows directly beneath it.
We don’t have any other material library except VRmats in our download section:
http://www.chaosgroup.com/en/2/downloads.html?s=v-ray-materials
Please note that the slowdown in the rendering depends not only from the materials but from other factors like lights, global illumination and etc.
If you still have troubles with scene optimization you could pack it up and sent for investigation (FTP could be provided if needed).
