State of the overlay tree branch?

[Sebastian Sturm <s.sturm@arkona-technologies.de>]

Hi,

after finding that the feature/noverlay branch does wonders for my 
editing experience[1], I'd like to reinvigorate the discussion on its 
inclusion into master. Are there plans for a merge with the emacs-27 
master branch? Any critical issues blocking such a merge?

If a recent Emacs 27 variant with the overlay branch feature was 
available, I'd be happy to evaluate that in my daily work.

best regards,
Sebastian Sturm

[1] I'm using cquery for my C++ editing needs, which comes with an 
overlay-based semantic highlighting mechanism. With my emacs 
configuration, lsp-mode/lsp-ui emit 6 calls to line-number-at-pos per 
character insertion, which consume ~20 to 25 ms each when performing 
edits close to the bottom of a 66KB C++ file (measured using 
(benchmark-run 1000 (line-number-at-pos (point))) on a release build of 
emacs-27/git commit #9942734...). Using the noverlay branch, this figure 
drops to ~160us per call.