Yes and it's even worse than you think... The characters are not even raw characters, they are “boxed” into data structures and then the linked-list code guards

Yes and it's even worse than you think... The characters are not even raw characters, they are “boxed” into data structures and then the linked-list code guards them with a “thunk,” so “If I have computed this char return the cached char, else compute it and save it to the cache and then return it.” The performance is good enough for teaching and learning and mocking out examples... But the reason for the user libraries is that real string processing workloads need something way better as their default.