Ex-browser dev here. Please don't ship invalid HTML like this.
Web standards specify how to render valid HTML in a standard way, and browsers have become better and better at that over the years.
Invalid HTML destroys all that. Each browser will have to guess how to repair and fill in the blanks on malformed incomplete tag soup, and there is no one right way to do that. Browser X will make different guesses from Browser Y, and the next version of each will be different too.
Please just write actual HTML that is valid and your website will render much more consistently and reliably across shifting platforms, browsers and versions. It is not the size of HTML that slows the web down anyway.
Web standards specify how to render valid HTML in a standard way, and browsers have become better and better at that over the years.
Invalid HTML destroys all that. Each browser will have to guess how to repair and fill in the blanks on malformed incomplete tag soup, and there is no one right way to do that. Browser X will make different guesses from Browser Y, and the next version of each will be different too.
Please just write actual HTML that is valid and your website will render much more consistently and reliably across shifting platforms, browsers and versions. It is not the size of HTML that slows the web down anyway.