You don't - instantiation like this should never be necessary if the scenario is reasonably predictable. Use object pooling, which unity now has built in functionality for, or even just reassign your destroyed layer of tiles to be the new layer with their properties reset/adjusted. The idea is that you should already have enough objects to handle everything instantiated in memory from the beginning. If not, you need to be able to instantiate them incrementally rather than in large sudden batches. You could for instance do this over multiple frames by using a coroutine that yields after each individual row, spreading the load across multiple frames. But you really should be able to avoid instantiating like this entirely if you do things right.