>>25
Truthfully I have a fairly crude notion of this myself, but consider the following questions: What objects have the same memory location (eq? each other)? What order are internal definitions evaluated in, especially with regards to mutually recursive internal definitions? How large is the numeric tower? What compound data structures have copy-on-write versus mutable implementations? Can the way continuations are implemented make programs slower, even if they are used appropriately? How do you call foreign functions in Scheme? etc.