Performance of jQuery Selectors with ID

Question

I know in jQuery if we use ID to select elements,it\'s so efficient.I have a question about this selectors:

please consider this 3 selectors:

Answer 1

I would say that the first one is the fastest because you're simply searching for one id.

And

$('#Mytbl .MyClass')

is the slowest because you're not specifying the type of element that has the class "MyClass"