Okay, now I have to admit that the development speed and progress are amazing!
Just pulled new version, rerun build and now all the things are fixed: the file interaction works, CPU and GPU load reduced dramatically, and straightforward attempt to edit a medium-sized C project was successful!
Interestingly, #zed automatically found clang and uses one to analyze files without any questions.
Now the app looks a solid dev-version not like a PoC. I think one can even use it for some projects to investigate the features