Yeah, no. Javascript manipulates the dom exactly as you are describing. In fact, javascript is directly responsible for much of the rendering on the modern web today. Hacker News goes in circles talking about it lately, in fact.

So any page with javascript is going to be slowed down precisely for the reason you are stating.

All you have done is compared a bunch of chrome extensions. Adguard is not an extension. Being faster than all the extensions is like being smartest boy who got held back a grade.