I guess it’s just a question of time and resources. @jps and @wbond go the hard but efficient way creating the editor on very good low-level frameworks, which requires a lot of work and effort behind the scenes, while VS Code and Atom choose the lazy way by using a bloated web browser engine to built a text editor on, which comes with many rendering features already out of the box, which is to be paid with a lot of overhead and poor performance and huge memory usage.
Good stuff, just needs its time.