The most commonly used (dynamically allocated) object in the interpreter is the AT structure, by which conses, numbers and pointers are represented. ATs may well make 70% or more of all objects to be handled by the interpreter (my guestimate).
Since they come in such large numbers, I treat ATs special and allocate them in a dedicated list of blocks (Lush currently does this, btw). This helps alleviating the increased resource demand that comes with the new garbage collection scheme. First, I do not need to store address-memtype assocations for AT objects. This saves some space and decreases the n in the O(n) lookup time for all other addresses. The mark bits for ATs are stored in the blocks themselves, and marking an AT can be done in essentially the same way as in Nickle. That is, constant-time marking for most managed objects!
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