Speed of generators

How fast are JS generators when used as iterators?

To be clear, I see the

for..of

for..of

for..of

for..of loop being very slow compared to a plain

for

for

for

for or

while

while

loop when used on arrays. Is it because the

for..of

for..of

for..of

for..of loop is inherently slow or because the iterator behind it is slow?