Question

Is it crucial for performance to have ViewHolder as static in a ViewHolder pattern?

A ViewHolder object stores each of the component views inside the tag
field of the Layout, so you can immediately access them without the
need to look them up repeatedly. First, you need to create a class to
hold your exact set of views. For example:

static class ViewHolder {
  TextView text;
  TextView timestamp;
  ImageView icon;
  ProgressBar progress;
  int position;
}

Answer 1

It’s not crucial for performance, it is about using. If ViewHolder class will not be static – you have to provide instance of parent class:

No enclosing instance of type Type is accessible. 
Must qualify the allocation with an enclosing instance of type Type 
(e.g. x.new A() where x is an instance of Type).