Makearray slows down excel considerably

Bitten by the 'spill array' bug, I have attempted to revamp my way of using excel by replacing every single one of my previously used method involving having a formula in every single cell.

This led me to find alternative for sumifs and lo and behold, the same effect can be achieved by using combination of makearray, index and sum.

However, I noticed that this approach slows excel considerably to the extent of excel recalculating even when im hitting the delete button on blank cells. Annoyed by the lag, I switch back to my old method of not spilling sumifs and voila, the lag is gone.

It would appear that spill array does not necessarily increase excel speed under every circumstances