NewTab Adapter od Dahan Gong

This web extension takes over your browser's new tab settings, and it can move the focus of a new tab from address bar to page content.

This extension runs Vimium C's content scripts on its newtab page by default, while this feature can be disabled by an advanced option.

It also provides a vomnibar.html so you may set Vimium C's "Preferred Vomnibar Page" to moz-extension://<UUID>/vomnibar.html , and then Vimium C's memory cost will be somehow less.