- Garbage collection can be incremental, rather than being done
all at once. Garbage collection can occur in short pauses at frequent time
intervals, rather than in one long pause.
- Time spent in collection is proportional to amount collected
rather than to address space.
- More complexity in system functions ( cons, setq,
- Requires storage bits within each cons cell, or other clever ways
of representing counts.
- Cannot garbage-collect circular structures (since reference count
never becomes zero).