Landscape material problems

I’m trying to use two splatmaps to paint my landscape.

PROBLEMS:

There are black spots on my landscape.
The material consumes much ram (streaming textures loop).

SPECIFICATIONS:

GTX 980TI
i7 4790K
16GB DDR3

CONTENT:

In the post I’ve attached a picture of my landscape and a photo of my material.

Please, can anyone help me? :slight_smile:

Is there a large version of these images or am I doing it wrong?

Chrome example: Right-click the attachment’s thumbnail -> Open image in new tab

Can anyone help me?