What is object allocation fast-path in CRuby and how does it avoid malloc overhead?

CRuby uses preallocated heap pages and free lists to allocate objects without calling malloc frequently.

Ruby GC manages memory in pages containing fixed-size slots (RVALUEs). Allocation pulls from a free list instead of calling malloc each time. Only when pages run out does CRuby request more memory from OS. This reduces syscall overhead and improves allocation speed significantly.