Final answer:
Heapsort has a time complexity of O(n log n) and is not slow because it runs in quadratic time.
Step-by-step explanation:
Heapsort is not slow because it runs in quadratic time. In fact, heapsort has a time complexity of O(n log n), which is faster than some other sorting algorithms such as bubble sort or insertion sort.
Heapsort works by building a binary heap from the input array and then repeatedly removing the maximum element from the heap and placing it at the end of the array. This process ensures that the array is sorted in ascending order.
While heapsort may not be the fastest sorting algorithm in all cases, it is still widely used because it has a guaranteed worst-case time complexity and can be more efficient than other algorithms for certain types of data.