https://github.com/solidstate-network/solidstate-solidity/blob/d1ba52d0981e3d1e1feda525dca8dd0c07ea4a00/contracts/data/BinaryHeap.sol#L251C1-L259C6 Heapify procedure is used in every add/remove operations. Heapify has while loop that call another heapify function exactly len/2. It's O(n).