Principle 4: It's an art, not a science
It is important to remember that graphics optimization is an art, not a science. In most cases, there is no single right answer on how to fully optimize graphics as the route you take will depend on what you are trying to achieve.
In general, a common goal to aim for is to render something on-screen that is both visually appealing, and does not hinder your application’s performance.
So don't be afraid to experiment with the algorithms and use faster approximations if it helps streamline performance. It’s unlikely that anyone will notice if an optimized version of something on-screen is not bit-exact.