To sharpen your statement, the cost is missing the CPU caches, which is often caused by failing to pool allocations and reading indirectly.
> But the argument is you're trading some of that performance optimization for maintainability.
Right, but exactly how much? I would argue "very OOP" design styles neuter your ability to optimize the system, and sometimes necessitate that you are kept at arms-length from the system, only capable of "customizing" it via more abstract API layers. I do believe certain OOP practices can make maintaining software easier, but I also believe we have not figured out how to retain control over the computer in the face of these abstractions.
As an example, Clean Coders advocate for "separation of responsibilities" and often speak in terms like "ownership" or what a function/class "knows about" or "should have to know about." When different classes are given different data-fields in the pursuit of making it clearer (what should exist in that scope,) you are creating a constraint which is virally spread through the codebase which runs counter to what the CPU wants. The CPU wants an array, but you can't have an array because the FileManagerFile can't "know about" the FileManagerFileCache, and the FileManagerFileCache can't known about the FileCache, so now each FileManager "owns" its own cache, which is an entirely separate heap allocation.