I've written the parser myself, adding features as needed. The C++ spec is incredibly complex so I'm not exactly sure which versions are fully supported. But hopefully it covers most things.

I measure the 10x performance all the time. But it's not possible to compare like-for-like with other editors unfortunately.

10x has been tested on Unreal Engine source from the start, which is many millions of lines of C++.

I don't use a GUI tookkit. I write the UI system myself.

It doesn't support LSP.