Is it always worth checking for null pointers?

Let's say we call a method on a variable fetched through findViewById():

TextView tv = (TextView) findViewById(R.id.text);
tv.setText("Some text");

Android Studio automatically warns us that setText() may produce a NullPointerException if tv turns out to be null. If we however are certain that tv will never be null (unless something really wonky happens which should crash the app anyway), is it really worth encapsulating the method call within an if(tv != null){} statement? What if these two (or more) rows are executed very often? Can we gain any significant performance increase?