Some game engines (C++) do allocations in multiple memory areas. If some allocated memory is known to be needed only for the current frame, then it is allocated

Some game engines (C++) do allocations in multiple memory areas. If some allocated memory is known to be needed only for the current frame, then it is allocated from that memory area. Then at the end of the frame the whole region is freed. This is an explicit garbage collection at end of each frame. Memory allocation can further be split according to the CPU thread, thus avoiding global locking in the allocator. With double-buffering the next updated/prepared frame can use its own memory area, while the previous one finishes rendering. The problem with GC or with reference counting is that it needs to operate on each allocated object separately. If the task for the GC can be reduced to operate on whole memory areas only, its overhead is greatly reduced.