It turns out that you count from 1 to 4 or 5 very quickly indeed. It’s as if you know how many there are just by looking at them. That’s one of the theories put forward anyway. It’s so quick, it’s not even called counting: It’s called subitizing.
Above that number, it takes 2-3 times longer per item to assess the quantity. That’s normal counting.
That’s why it’s faster for you to sort out items into groups of 3, say, and count the groups. Subitizing is that fast.