We try to use a single command buffer per frame.
We create a MTLBuffer for every shader to store the uniform variables.

In a scenario when we use a same shader more than once in a single command buffer, we create a new MTLBuffer after every draw call for any shader.
The results in allocation of several MTLBuffer objects while encoding commands.
This can be improved by using a MTLHeap instead to gain 2-3 FPS.