Copying GC's may be slower to collect if you compare the speed of identifying live/dead objects versus object identification and copying of live objects but the

Copying GC's may be slower to collect if you compare the speed of identifying live/dead objects versus object identification and copying of live objects but they have a significant improvement in the speed of allocation. Copying GC's allow you to perform allocation by incrementing a pointer, whereas non-copying collectors force you to traverse all the free blocks in the heap looking for a suitable allocation spot, similar to what malloc(). As the heap fragments over time this cost becomes greater and greater. Copying GCs can also improve memory locality during collection which a non-copying GC cannot do, giving a general performance improvement for the application.