I'd say that the needing rewrites is bad for the future clarity of the code. So much so that people conclude the 50% performance hit is worth it to use open pol

I'd say that the needing rewrites is bad for the future clarity of the code. So much so that people conclude the 50% performance hit is worth it to use open polymorphism (interfaces, etc.) over closed (tagged unions, algebraic data types, etc.). So I optimize for the ability to reason about over the lifetime of the project above the current ability to reason and above performance (with exceptions). What is adding a polygon going to do? Either back to the 'bad' interface to hide variable object size, extend to a tagged union with a size of the biggest datastructure - hurting cache performance each time it grows -, or an involved Object of Arrays structure - not good for clarity but great for performance. All while having to remember which field, width or height, to use for the circles radius.