I understand what you mean about less kilobytes and loading faster. However, using jquery will not make it slower.... how much time we talking about here? 2-5seconds? And that's a maybe.

More Companies and professional websites are turning to Jquery.

Dojo is similiar to Jquery but it has wayyyy to much file size. So I would understand if he were using it.

Sorry but using jQuery will not make it so slow, that you can tell the difference visually btw JavaScript.

It's your choice I respect that.