title: Shader position vec4 or vec3
body: <p>I have read some tutorials about GLSL. 
  In certain position attribute is a vec4 in some vec3. 
  I know that the matrix operations need a vec4, but is it worth to send an additional element?
  Isn't it better to send vec3 and later cast in the shader vec4(position, 1.0)?
  Less data in memory - it will be faster? Or we should pack an extra element to avoid casting?</p>
  
  <p>Any tips what should be better?</p>
  
  <pre><code>layout(location = 0) in vec4 position;
  MVP*position;
  </code></pre>
  
  <p>or </p>
  
  <pre><code>layout(location = 0) in vec3 position;
  MVP*vec4(position,1.0);
  </code></pre>